I was on the electric car race team at school, so my experience is fairly old and might not be relevant. However, in my experience, when something in the drive train broke, it wasn't bad to replace it, but it was borderline catastrophic.

In one weekend, we had two controllers go. The first time it resulted a small electric fire. Lucky it was in the garage and we were able to put it out before anything happened.

The second, was when we were walking the car from the pit to the garage after some testing and the result was instant full acceleration. It went from coasting to spinning the tires looking for traction to just GO. The driver was quick with pulling the emergency disconnect, otherwise you can imagine how bad that would have been, there were people everywhere.

Hopefully, things have gotten better, but when they did go wrong, they went really wrong.