I understand your position, bunnyrabbit, but I also understand hers.
A couple of years ago, one of my nieces graduated college and went job hunting. It didn't work out well at all...no jobs available in her chosen profession.
I thought I'd help her out a bit. I made a few phone calls, thinking I was helping her out. At least two of the positions were a lock for her, all she'd have to do was show up sober for the interviews, with her scholastic record and recommendations, etc. in hand.
I made a big mistake. I'd forgotten what I was like at that age, but I remembered really fast when she started yelling at me about her independence, not needing help with anything, not trading on my name...the whole nine yards. And she was right, I should have minded my own business.
By the way, right now, she's still looking for a permanent job. She's got three part-time crap jobs for some income, and still lives with her Mom...but she's independent as hell, right? In her mind, she is...and it makes no difference whatsoever what I think.
She could have had her own home and a great car by now, all on her own hook. But no, she needed to do it "on her own".
Jeesh, all I did was set up interviews. If she was no good at the job, she'd be out of any of those positions in pretty much of a heartbeat. She didn't understand that all I was doing for her was getting her foot in the door so she could prove her own worth to the folks that mattered, her new employers.
I will still help her out anytime that she asks me to help her. But that's what it's going to take, asking. And I may think about it for a while first, before acting on it.
...and life goes on...
@flyingmd wrote:She has every right to be upset and frankly you are wrong. I also agree that 4 cards is totally overkill and sends a very irresponsible message about credit cards and using credit. What 20 yo needs 4 cards off the bat like that??? What I did with my daughters is have many conversations over time about the need for credit in this world and how it is a huge responsiblilty which can get a person into to major financial and emotional distress if not handled properly. I discussed with them the difference between AU and having their own card and the decision to make them an AU was discussed in advanced as was the timing for when they should start to build their own credit histories and the benefit of having an excellent credit/financial history. On a positive note, it sounds like your daughter is a very astute, intelligent and responsible girl. She obviously learned the the seriousness associated with the use of credit from somwhere. Also keep in mind that over 75% of identity theft is committed by family members and /or friends. Using someones SS number like that without their knowledge is just plain wrong. Even if it is only as an AU. Not that I am accusing you of identity theft, but I know several examples where the the theft was done by a parent to a child atfter the parent got themselves into financial hot water and started using their childrens SS number to get credit. This to me is despicable and a violation of trust and security to the person who depends most on that trust and security, a child. What an awful way to go out into the world, with multiple blemishes on a credit report because of an irresponsible parent. I just think that a persons SS number in this day and age should be protected absolutely and that the decision whether or not to hand that number out to a credit card company or anywhere else should rest with that person. Not their parent, child, brother, sister, etc. Sorry to sound to negative, but I am only giving you my opinion because you asked for it in your initial post.
Just so that we're all clear on this subject, this isn't about identify theft (I know that's not what you're saying, flyingmd, but I just want to make certain that everyone understands that).
What bunnyrabbit did is what parents do all the time for their teens & young adults. Most, like bunnyrabbit, do it without a second thought, because they're not leveraging their childrens' clean/unblemished names to gain credit or services for themselves (identity theft). They're providing access to their own credit for their children. Lots, and lots of parents do it. When children are traveling with friends & relatives, it's not at all rare for parents to hand them an AU card to use, as oposed to cash. Heading off to college? Mom or Dad pull DD or DS aside, give them a quick primer on using it "for emergencies", and stash a card in their hand (only to reposess it at the midterm break, LOL!!!). Senior trip-- a credit card frequently gets handed out. First job out of college, child moves halfway across the country with no savings, and only the promise of a paycheck? Mom & Dad frequently hand them a credit card. Kids (older teens/young adults) are being left at home for the 1st time while Mom & Dad travel? Sometimes they leave an authorized user card for expenses while they're gone.
My point is that it happens all the time, without consideration for "credit building" for the child. It's usually convenience. My father made me an AU on a credit card when I was only 16 (my older sister was too irresponsible), when we started driving, and dating, etc... I think he was scared that we would be caught somewhere without cash, and have need for a method of payment. He didn't ask or consult me. He just gave it to me, and made me swear not to let my sister get ahold of it, LOL! <-- An emergency trip to the mall might have been in order if she had. 
I never used it until I went to college, and he instructed me to use it to buy books, etc.. (it wasn't one that reported AUs, apparently, either), but it was about a parent providing access to *his* financial vehicle, not about my own credit history (or lackthereof).
Bunnyrabbit understands the value of having good credit, and how difficult it is to establish credit for a young adult, under the age of 21, in this day and age. She mistakenly thought that her daughter would be pleased by recieving a hand up. It was a hit or miss proposition, to be sure, but I'm certain that it was done with only good intentions for her child. I suspect that her daughter doesn't fully understand the nuances of credit & finance, or else she might just accept this unexpected gift **until** she could establish her own credit history. This, because I don't know many 20 year olds who wouldn't jump at the chance to not have to pay deposits for cell phones, or higher interest rates on cars, and insurance, etc... Very few 20 year olds have reached an affluent financial state without the assistance of their parents/relatives/guardians/benefactors, anyway.
The only difference in what bunnyrabbit did, and what hundreds of thousands of parents do all the time (in good faith) is the forethought of her daughters *credit report*-- desired or not. My father thought it more convenient to pay certain educational expenses of mine with his credit card (in my posession). There is no doubt in his mind that he gave absolutely no consideration for what, if any, impact it might have on my credit, being an AU. He doesn't hang out here at the FICO forums.