Highbrow? Lowbrow? *Furrowed brow*

There's a quiz on Radio 4 called The Third Degree, in which a team of three students are pitted against a team of three dons. One of the rounds is called "highbrow/lowbrow", in which the contestants are given a single word and asked if they want a highbrow or lowbrow question connected with it, with the other question going to their counterpart on the opposing team.

On this week's episode, the final word was "underground". Here are the questions:

Highbrow:
[clip of "Subterranean Homesick Blues" by Bob Dylan]
Amongst the torrent of extraordinary urban imagery in that song, can you complete the quote from the end of the second verse?

Lowbrow:
[clip of "I'm Sticking With You" by The Velvet Underground]
The song was revived by being the music behind an award wining Hyundai car advertisment. This might well have delighted the father of pop art, who was closely associated with the band. Can you name him?

Now, can someone explain to me why one question about a 1960s song (which just asks if you know the lyrics) is highbrow, but another question about a 1960s song (which is actually "Who was the father of pop art?") is lowbrow? Just because the latter was in an advert somewhat recently (a fact which had nothing to do with the actual question)?