>company by revenue

This is dissembling by picking the metric that measures literally the exact opposite of productivity. SAP has the same number of employees (more?) as eg FB but its net income is 1/10th.

Are there companies with FB-like metrics outside of US at all?

I guess not (honestly don't know) but if there aren't then that seems to be more evidence in favor the idea that American devs are more productive, not less.

You can't just map metrics/profit to employee productivity; it should be obvious there are so many other factors.