I don't understand why interview tests are so prominent, why not just hire the person as a test for a bit and fire him if he's not up to par? Doesn't cost much and is a much better predictor of success in the company
It costs a lot to hire someone and onboard them. And, if you make a practice of firing people after 60 days because they aren't a good fit for whatever reason, you're probably going to find that you have a hard time hiring anyone.
As I said in another comment, (paid) interning and hiring someone as a contractor/consultant for a fixed period are great for situations where it works for everyone. But, if I'm looking for a new full-time position, I'm almost certainly going to pass on a position that doesn't carry with it the presumption of ongoing employment.
[ADDED: And, yes, some companies have an official probationary period but AFAIK that's mostly reserved for when a hire really isn't working out for some reason.]
