Good point, but not unsolvable. I can imagine the law would require user specifically giving permission to delete the data afterwards, maybe even mandating a certain form of presenting the gist of the deal, instead of lengthy and indecipherable TOS.

I don't know the legal language, but requiring a text box with a tick mark or equivalent that presents a legally mandated predefined statement designed as a short and simple (unlike most TOS and EULAs), in clear and visible text, should not be impossible.

For example, "I agree that $corp may delete my data without notice and opportunity to back it up" if the $corp isn't willing to offer a TOS that grants the user those rights. Possibly another similar one about privacy.