In my country (Poland), cabs are not regulated very heavily, which leads to a flood of drivers, and low prices. In result, in many towns even by driving 10 hours a day (most of which is spent waiting for customers) you're making not much above the minimum wage. As a result, driving a cab has become in large part an extra source of income for retired cops or other people who retire early (say in their fourties).

I don't see nothing wrong with that - it's a job that requires no qualifications, has no boss, flexible hours, is not demanding physically or intellectually. In short - a dream job for many people. It only makes sense for it to pay less than say a grueling job at a factory.