The big issue with email is not that the content is breaking the law, but that all the metadata of every account, every contact, and the sum of your internet activity is flowing through their servers.

And while it is true that a VPS provider can access that, the big difference is that they'd have to go out of their way to snapshot memory, as opposed to a streamlined repeatable legal process (that scales because they're running the software) with the big "privacy providers".