I think I understand. I have a VitaTV and I was going to buy Persona 3 Portable for PSP for my girlfriend off of PSN, and let her download it on the VitaTV and play it on the TV. But when we tried to log her in, the system threw a fit about her not being the one registered to the console and stuff

PS3 and 4 let you switch out users easily, so it probably goes together with switching e-mails and regions and stuff pretty easily. The Vita likes to lock itself to one user, and also to one region. Kinda sucks. Sorry about your luck then