I compare it to 'the confessional'. Because all they can see is the back of your head, they think they're in the confession box and open up and tell you a lot of personal stuff.
My most memorable one was driving a young one from Summerhill out to Blanch. Her boyfriend was in the navy and just back after a few weeks at sea. The GF rode him senseless and told me the details. I felt sorry for the guy! That got us halfway to Blanch. The second half involved a 'love triangle' of sorts between her, her father and a 'knacker' girl. The father must have been a diabetic (or a drug addict) and he couldn't get it up. So I think the daughter said she had to inject him in his penis (don't ask me why). But the traveller girl thought he had money and was trying to get on his romantic side & maybe move in and get the house/flat. The daughter wasn't happy naturally. So there was loads of verbal/physical fights over the past weeks. The daughter was a big girl too so I wouldn't like to end up on her bad side (
or her good side either)
I don't think I said more than 3 words during the whole journey and I had to take a break after it to recover
Anyways, at the OP; you have a right to a quiet journey so if you don't want to talk, you don't have to. That's why we ask you an opening question about the weather or something trivial. We don't care what you think - we're just seeing if you're a talker or not. As someone else said, reading your phone is a good indicator as well.