You answered your own question.

You also don't know what they're listening to. Personally I'm listening to either NPR news or audiobooks. I ride 2 hours a day, every day, year round. Ambient sounds are great and I do ride without the bud once in a while and enjoy it, but all winter long there's nothing to listen to but the wind, and I hear birds and nature at home all day. Ride time is one of the few times I have to get some books consumed.