Its quite complicated and sorry in advance for the long post. But up until age 16, soccer competes with the other big 3 sports surprisingly well on the mens side. The problem is two fold:
1. The best players are forced to play 'club soccer' and the top teams of those (which there are thousands at all levels, genders and age groups) are forced to pay a lot of money and travel very far distances to play against the best competition in the best leagues and tournaments. The hot bed areas over here are North Texas (Dallas), California, Chicago, and Washington DC to New York, but because of training and financial commitments, a lot of the lower socio economic athletes in the inner cities are unintentionally frozen out. Of the other top athletes that can afford the time and financial commitment, some of best top players on those teams will get recruited for and play college soccer for four years which, although is a very high standard of amateur play, is purely results based and is set up all wrong for pro development. Its also is not very glamorous compared to college american football and basketball. The very very best will play in pro academies (like UK) and will all attend the same school in the mornings, practice in afternoons and fly to games and get great competition and coaching. However, these academies are still relatively young vs the Euro/South American academies and even though it gives a good supply of talent for the MLS (pro league) it has yet to produce any top talent capable of infiltrating the top world leagues. The very best like previously mentioned Reyna and Pulisic get picked off by Euro academies and either make it there or fade away and just return stateside to MLS. They also had connected dads that had better connections than most which I'm sure massively helped. More and more top euro scouts though are getting active over here as the game is improving slowly but surely.
2. For most though, around 16 interest trails off some in the sport as am football especially is massive in high school and is the attention sport to play on Friday evenings under the lights where games against the biggest schools can have crowds up to 5000. Also adding to this fading interest is there's not much scholarship money available in college for soccer vs basketball and Am Football and the best athletes look to that and the glamour of competing in those sports in college which, as some of you know, can attract crowds of over 100,000 in the Saturday american football games.
The women's game is set up quite similar but they dont have the massive animal that is american football to compete with for the best female athletes.
