For what it is worth, the ave US club level is pretty much what it is in Korea, and the one time I was able to hit in a German "club" that was really a gym hall that had 24 tables setup for its TT verein members to play training matches, I saw the ave level was also similar to SD Mean or Ave US level.
Think what level 40+ yr old adult are when they take up the sport and all they do is play matches for 4-10 years and you got a good starting place.
Now Germany, BS and others will clue you in, has a really great participation level with a lot of numbers and a really great league infrastructure, even if those numbers have been declining the last decade or so. So naturally with early start and dedication, there will be a LOT of really good players and Germany has a TON of players, several hundreds of thousands me thinks, USA has MAYBE 4000-5000 doing sanctioned tourneys and maybe a total on the optimistic guess of 30,000 players who play seriously in churches, rec centers and the few US clubs you can find who do NOT do sanctioned tourneys. That is it. USA TT scene is still pretty bare and meak, but percentage wise, it is exploding like crazy. However, the tiny puny numbers we have had make even a 100x explosion growth of players and clubs look pretty small insufficient to make it even 1/10 of how easy it is to find TT action in Germany or Korea (who has prolly 1/4 the TT density per capita).