It's not. The first time I ever saw kids playing soccer on their own with no adult supervision was when I left the US. I haven't seen it since I've been back. I think that's the most glaring "issue" right there.

Correct. We actually don't play "football" properly as a street sport either though... its typically a flag style football (two hand touch, etc) but the main sports are (generally separated by season during school) football, hockey/basketball, baseball.

This is part of it, but you only need a few dozen great players to put together a program. Another part is organization. Italy has kids playing calcio in the streets by default, but FIGC has been run poorly for decades. USSF tries, but similarly is a little in over their heads.

the US has a large relatively recent influx of Latino populations, and they play a lot of soccer, and in a number of cultures also baseball