I think England is an interesting example. During the 00/10s they were struggling internationally. My understanding is the EPL was being dominated by foreign born players. A consortium of different orgs, including EPL, formed the EPPP in the early 10s help develop home grown talent. I think in recent years that plan is finally bearing fruit given their star studded roster.
Also, no doubt soccer is more popular in England, but I don't think that 40% number is super comparable to the US. I believe there's about 15k academy players and about 1.1-1.3m grassroots. Anecdotally I've heard grassroots is starting to show some signs of what club soccer is doing in the US -- just through conversations with friends. That 40% number includes playing on playgrounds at recess, etc. That all said, the participation number in soccer is definitely higher in England, but like the 00/10s proved, they too are vulnerable to low level playing internationally.
Finally, I think without a doubt pay-to-play is a massive problem for us in the states. I think we lose far more players to pay-to-play, poor player identification, development priorities, and BS politics most clubs have. The number of players we lose there far outweighs the number of players lost to other sports. Even all that said, I still stand by that there is absolutely no reason we couldn't implement something EPPP. There's still a large enough pool to do it. The challenge, of course, is who's going to pay for it.