Not just wage disparities. You can probably watch the typical video of an individual sitting calmly scrolling on their phone back at 32x speed. More complex scenarios with multiple people at 16-4x. Even assuming they pay 'car monitors' as much as drivers (which you're right, they probably don't) the cost for the monitors is still probably less than 10% the cost for equivalent drivers.

You probably only need to do that when something is reported as well.

Most likely a “data driven sampling methodology to identify the predictive factors of damage.”

Not just wage disparities, but also time / location.

Quickly going through CCTV footage from a ride to catch "unusual things" takes much less time than driving. Even if somebody had to watch the entire ride at 1x speed and just one ride at a time, there's no need to do it when the car is idle or driving to pick up the next passenger. You can also hire a lot less watchers than you have drivers, because a surge in demand in one city can be serviced by watchers in many other cities. There's no need for night shifts either, you can make everybody work 9-to-5 in whatever timezone they're at.