Kicking people off for accepting rides and then canceling them makes perfect sense because once you accept the ride, the customer is waiting and they're not looking for another driver. It also discourages drivers from looking at the destination and then refusing rides that legally they're not supposed to, like trips into black neighborhoods.

Accepting in the first place either happens or doesn't in only a few seconds, and if you don't they immediately go on to the next driver. At best they have the incentive to make you manually re-enable your availability to drive if you neither accept nor decline more than a couple of rides in a row, so they can stop routing rides to you if you're not actually there. In makes no sense to kick you off over it, so why would they do that?