In markets where employers have a lot of leverage, some employers do more or less do that. They hire more employees than they really need, then put in stringent

In markets where employers have a lot of leverage, some employers do more or less do that. They hire more employees than they really need, then put in stringent screening practices to cut the ones they don't want to keep. There are a lot of crappy employers out there, who can get away with it because many people are not in an economic position to object. In markets where employees have more leverage and can choose which employers to work for, using the legal right to fire people whenever you want to produce a trial period as a matter of routine is a good way to get a bad reputation. If a company is known for firing 30% of its hires within the first 6 months, many people with options will choose another option. Or at least, they will have to be much more attractive in other ways to make up for it (higher pay, more interesting work, etc.). If that's really the intent, making it officially a trial week up front is a lot more transparent.