I think I get what you're saying, but surely the same could be said about all self-control issues. Exercise and diet is "all" it takes to lose weight, but the question is whether you have the self-control to do that yourself.
Self control and will power are loaded terms for chemical and electrical operations of the brain; executive function is an improvement. Regardless, it isn't magic or special, just wetware ops. Bugs in the human hardware or software? We patch the human, if we can and if they wish.
I'm originally from the UK (now US), which doesn't score so well either (28%), but the differences are obvious - massive portion sizes in US from deli sandwiches, foot long subs, movie buckets of popcorn, giant size sodas. People driving everywhere rather than walking.
