Some companies in the US are terrible at getting rid of bad workers- too many cracks for them to fall through. Some, however, are known for paying high salaries and letting anyone go who doesn't live up to them.
Is that really the case? I would have naively assumed the typical (median) startup path is something like hire, hire, hire, go-bankrupt? And the successful ones more like hire, hire, hire, hire, hire, go-public?
Easy firing doesn't seem relevant to either of those?
Hiring is riskier, and therefore slower. There are 2 sides to it of course, on one hand employees are much more protected from losing their jobs, but on the other one innovation and fast access to jobs is also slower.
Also, it is not only about firing. Hiring is also slower because of all the paperwork that needs to happen. For example, in Spain you cannot just hire someone. You need to draft out a contract, cover every possible detail related to the work that the person will be doing, etc. it is just slower in general.
This brings me back to my min point though: employment at will.