Employee protection laws have nothing to do with what I was talking about. As an employee in the USA (contract or freelance), I can quit any time I like. My contract may be for two years, but I can cancel it tomorrow if I want, and only in extreme cases is there any penalty for doing so.
In the EU, if I sign a 1-year contract there is an expectation that I will actually work that year. If I break contract by deciding to get another job without negotiating early exit with my employer, I could be on the hook for damages. This doesn't come up very often because in the EU people just don't break contracts like this--if you want to hire someone you ask when their contract is up and work around that. But the reason why people behave this way is because the termination of a contract is a serious deal and hard to navigate.
The US is (mostly) at-will employment. One aspect of that everyone talks about is that the company can fire you at any time for almost any reason. That sucks. The flip side though is that you can fire your employer any time you like, and walk of the job to somewhere that pays you better or treats you better. This is at the root of a lot of American dynamism, and a good thing.
At-will employment is definitely something that cuts both ways.