There is a cost involved with onboarding/offboarding employees which is a common reason why this tactic isn't used. Between the time spend spooling someone up

There is a cost involved with onboarding/offboarding employees which is a common reason why this tactic isn't used. Between the time spend spooling someone up on your internal processes, completing required HR tasks, requisitioning equipment, etc it often makes it a pain to go with the hire/fire quickly method. I'm sure you could build your business around it, but at that point you might need to look at the moral of the company. Also, if you fire someone in California they will likely file for unemployment which means your UI reserve account requirements might go up.