In France, for example, you have 4 months (and you can renew it 3 more months so 7 in total) probation period. If you need more then 7 months to realise you've made a wrong hire, then I think you can spend take a few more months to fire someone and not decide to fire someone at a whim.
Yes, that makes my point. During probation hiring and firing is easy. After probation the hard choice is made (they can fire you easily right before the end) and firing is hard.
