They are usually defining the specifics of whatever contract the company offers to their users, be it the sales or whatever services the company is providing. I don’t know which legal system you’re living under, but such additional clauses added to the base contract can very much be explicitly or implicitly agreed upon.

Edit: Of course this particular rendition of “We’re allowed to break the law - no take-backsies” won’t stand anywhere consumers have like any rights at all.