They're a blue collar guy trying to feed their family on a low-wage job with variable income, they have like zero incentive to do so man. They're also gambling that they can potentially intimidate a rider who says they won't pay x price because of a detour, mistake, or misquoted price. The driver could be larger or tougher than the rider, and you're in a small space with them.

I had a larger driver try to intimidate me into giving them a cash tip on top of the one I'd already written in via credit card. (I refused). This is why I never, ever use taxis now