No, in no way do these questions say "Yes this person can do the job." But I think general trivia questions are being used to find out if the person is a good fit for the team. I think you can learn a lot about a person by looking at their frequently visited online sites.

For example, most of my coworkers look at me with a baffled expression when I mention a lot of the sites I visit. Though just about everyone I work with is a programmer, I think I'm the only one who has been to Joel Spolsky's site. I'm pretty sure I'm the only one in the company to visit Perlmonks (though there are a few people who claim to know Perl (I say claim because I've shuddered at some of their Perl code)).¹

I spend a fair bit of time online, I like to work with others that also spend a lot of time online -- or reading. If I say "Pragmatic Programmer" I expect that a programmer should have some clue what it is (and hope that they've read it, but my personal reading list is already huge, I can only read so much in a day -- so I can understand if they haven't read it).

¹ Update to add: I'm not claiming that visiting Perlmonks is a prerequisite for knowing Perl. Nor is visiting Perlmonks going to indicate that you know Perl. But having some vague notion of the things that I find to be very common online is a definite plus.