I'm going to need to see some data to back that claim up. ED crowding has been a major problem in the US, but not really so much in Europe, Hong Kong, etc. [1] If you mean total capacity, that's a bad comparison because the US population is huge compared to most developed countries, so of course if capacity needed is a % of total population then the total capacity will be similarly large.

[1] https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1553-2712....