Varies from country to country - normally taxi drivers are pretty near the bottom of the economic heap
If you are unlucky you'll be in a country where the taxi driver PAYS the company for his taxi and the job is an opportunity to make it up on the extras (like Ryanair TBH) - so they use cheap fuel, they go long routes, pass counterfeit currency, make off with any baggage you forget, and, in extreme spots, deliver you to their mates in some favella who will rob you or hold you for ransom.
Some of these are unlikely in the UK ..............
