True, but in fairness, the US is also a rather litigious society, and improper termination is one of the things people are inclined to sue over. That's why mature companies tend to put some procedural obstacles in place to keep managers from firing people at the drop of a hat. Typically the manager has to show a long series of specific deficiencies in the employee's work and attempts at counselling and remediation before they are allowed to fire someone.

Things are sometimes done more quickly at smaller places, but even then it's fairly common for employers to offer termination agreements, typically for a few months salary, to avoid even the possibility of litigation.