How interesting. That inverts expectations: you need a reason to fire a contractor but no reason to fire an employee.

Ah, I see it:

> Whether the employer has a right to fire at will or whether a termination gives rise to an action for breach of contract; and...

You can't fire a contractor when you haven't written in end-of-contract terms in there. i.e. when you contract with someone and you say "I hire this person from time X to time Y for money Z for delivery of A" you can't just abort sometime in the middle and be like "welp! off you go then".

However, it is perfectly reasonable for you to have exit clauses in your contracts to say that you pay per ride and that either party can exit the contract at any time.

i.e. it determines whether the 'firing' is a breach-of-contract situation

Okay, that makes sense, but it's not a factor in this case. Only a naïve reading makes it work that way but that won't work if you have the exit stipulations.