In many other countries you can not fire someone by default (it's illegal) so calling it a powerful tool sounds wrong.

In what country can you not fire your own employees?

In Sweden you cannot fire people on permanent contracts (that you need to give after 2 years) if you still require their work, i.e., you cannot fire someone without cause and then hire someone else to their exact job. In the Netherlands it is also extremely difficult to get rid of an employee with a permanent contract that you need to eventually give to them. In all cases I personally know of, permanent contract employees were basically paid by the company to agree to leave.

Does this not create an incentive for companies to rotate through short term workers rather than keep anyone on for more than 2 years?

The 2 years is an extreme if you abuse the system. Standard is 6 month probation and then your employment becomes permanent.

Tenure doesn't prevent you from being fired ever; it just requires a process to determine that you are being fired for cause. That is already the case for all workers in countries without US-style at-will employment.

In Bolivia, there’s a right to “job stability” in the constitution written in 2008. Supreme Court here interpreted it as “right not to be fired”. There is precedent of people complaining to the ministry of labour asking to be hired again after getting fired and getting away with it. It’s stupid, but it’s a counter example.

For example german academics suffer from the fact that they have to change state after some years. Short term contracts can only be prolonged so long. After that you get a permanent position which university rarely wants. Therefore they tell you good bye. And that is because it’s almost impossible to fire someone with a permanent position. (Not the best source: https://www.timeshighereducation.com/unijobs/article/academi...)

    In what country can you not fire your own employees?

In Germany, you need strong reasons to fire an employee: intentionally causing accidents/damage, theft and other felonies related to your work (so, no firing your employee for drunk driving off the job) or failure to improve performance. The other thing is due to closing of the department or the location or the company going bankrupt, but these cases are often enough fought over in court and especially if the company is not bankrupt it's difficult to get someone fired.

Very interesting, honestly I prefer the American system where you can be fired at any time but if fired without cause you are entitled to continue receiving some portion of your paycheck from unemployment insurance.

The problem here is that you need to be able to afford the lawyer, the time for the court proceedings etc. in order to get said money.

Which means: those hit the most hard by "fire at will" are the poorest.

So if I am an employer in Germany and I fire an employee for misconduct but he claims I fired him for no reason how is the dispute resolved?

In many (most?) European countries you cannot legally fire an employee at will. There needs to be a process, and the employer has to be able to show that the employee cannot or will not perform even adequately (or actively harms the employer eg. by stealing), cannot be trained or reassigned to a more suitable position.

Countries where unions and work laws actually work, like many European ones.

Sure firing is still possible, but be ready to prove in court it was done properly.

Quick firing like in US, only if it was something really bad and even then, a notice period might be required.

Let’s not engage in Whataboutism. We’re talking about the US, specifically. In the US, specifically, being tenured and having protection against being fired is a powerful tool.

It's still a powerful tool in any country regardless if it's the default or not.

It's not a tool. It's a basic human right.