Generally I think that parents seem to try to do their best. Our oldest has an October birthday. The town was not going to let her go an account of being 'too young.' We felt that she was ready and sent her to private kindergarten.
I'm gonna be frank though and say that anyone who holds their kids back for 'athletic reasons' is an idiot. I totally agree with you about 20 yr olds at hs graduation. Do they think that college coaches aren't going to notice?
^This. Our son has a June b-day -- we never even entertained holding him back in part because we didn't want to pay for another year of daycare plus he never showed any of these (made up) red flags. Plus the sooner we get him out of the house, the sooner my wife and I can party and travel -- any parent that denies feeling that way to at least to a certain degree is a liar. Athletically, it's tricky. Some kids who develop early and dominate early thanks to being held back can still end up parlaying that into a scholarship -- some coaches want fully developed and game ready right out of high school. But most are going to factor in the age and more importantly the parents/genetics. One of the best things I've ever been told regarding kids and their athletic development is: You don't necessarily want to be the kid who is on everyone's radar at 13 or 14 because it gives college recruiters a loooong time to find your flaws. Four years of people tracking you and questioning your potential the minute you hit an inevitable plateau. Meanwhile, the kid who is young for his grade, has less to dissect due to a light resume but is sitting on good genes can often times be more attractive.