One of the great complaints of bosses and corporations is that they can’t fire people whenever they want to. Employee protections were one of the great victories of the 20th century and the union movement, though far more in Europe than in America, except in the Federal civil services.
But bosses do have a point: being able to get rid of employees without fuss isn’t unreasonable: they’re hired to do a job, and if you don’t like how they’re doing it, firing them makes sense.
At first glance the problem is that often such power is abused, in too many ways to recount.
But the real problem is that without a job, people suffer: they have less, they may wind up homeless, in the US they’re essentially cut off from medical care and so on.