I can talk to strangers for hours with confidence and honest interest in what they have to say, but only as long as the stranger and I have a pretext to be talk

I can talk to strangers for hours with confidence and honest interest in what they have to say, but only as long as the stranger and I have a pretext to be talking. Sit me and a stranger down in a room and tell us we have to talk about our opinions on package management, the best BBQ recepies or the latest Marvel film and I'm happy. It's the small talk crap that I can't deal with. When I'm in a line at a supermarket, I neither want to talk to my fellow shoppers or the checkout person. I don't want friendly banter from the person selling me beer at the pub. I can't be bothered with trying to turn a pleasantry, exchanged while holding a lift door, into a fleeting relationship.