It seems like the reason they're not including AU's on Credit Reports is to prevent tampering, such as when companies 'sell' AU's to give people a huge spike in score. It seems like the solution would be simple:
If you add someone as an AU, it only reports as of the date you add them, instead of reporting the entire history. This way you can still help someone establish credit, but you don't give them an enormous jump by (for instance) adding a 15 year account to their report. This would also prevent huge drops for housewives, who may have been added 10 years ago and will suddenly have that wiped out.
Is there something I'm missing here?