That might be because they actually aren’t binding in many cases. Courts have held that if the contract can’t be reasonably expected to be read or understood by the people it “binds,” it’s not really enforceable, and 99% of EULAs are ridiculously long and legalese-heavy. But that doesn’t change the fact companies can and will treat them as such until challenged in court, and they’ll almost always be allowed to refuse service to pretty much whoever they want.
So you’d be right here; grandma’s post about not giving Facebook the right to her data is meaningless. Don’t want Facebook to have your data? Don’t use Facebook!