
unfortunately, even in US, probationary employees can be let go for no real reason. Probation employees in some companies don't even get any benefits until they become permanent. Ditto with temps and contractors which is why more and more businesses are hiring temporary or contract workers (those bastards!).
Once you've become a permanent worker, the company will have to go through hoops to get a person fired (and employees have a right to dispute even sue the company to protect his/her rights).
Dowan in uniform (づ ̄ ³ ̄)づ