That seems like nonsense. Software cannot constrain the physical world. I could touch the bits on the drive itself, or I could physically destroy the hard-drive. Both would "truly delete" the data.
Good luck deleting data from my 5th backup drives that I didn't tell you about. It's not hard because destroying a hard drive is hard, it's hard because you need to find not one, but all of the drives that are likely replicated and distributed around the globe already if you ever intended to do business with that data.
It's not a technical problem to solve, it's a legal one. If there is a crushing penalty if data that was supposed to be deleted shows up one day, companies will find a way to delete it.
Umm you can. You can force companies to pass their code through an examination (even by a third party) and define a procedure of ensuring strict data hygiene. If they cannot pass each year, they will be subject to fines.
