When forced to make smalltalk with zero shared context with someone I find it a huge burden to avoid saying something weird, or offensive or too random, its like the filter is too strict to be able to say anything interesting so its not worth the mental effort. People who enjoy smalltalk seem to be much less sensitive to whether the person is interested or agrees and are more willing to take conversational chances.

I don’t talk to cab drivers either.

My girlfriend always finds a way to start conversations with ever driver but I rarely ever do unless I’m in some peppy mood.

The pressure to talk to barbers seems much higher though.

I treat my barber like family........ i need to look good!

Good point. It's always good to take care of service workers that do a good job.