is it though?
I have never seen any type of check on rosters, who the girls are that show up, etc. at any tournament (I will say we have only ever played USSSA and USA, really only options around here). now our nationals for this year (youth softball nationals) at least has parents digitally doing waivers ahead of time, so that might be somewhat of a deterrent (I know I would be reluctant to sign a waiver for someone elses kid). you could easily fake your entire roster, show up with girls all say 14 at a 12u tournament, and only if people recognized them, knew for ceertain their birthday, could you get called on it.
does softball need something like soccer has, where each player gets an ID card each season, and officials check them all at start of each game (along with checking cleats, etc.).
I don't believe there are many actively cheating and having girls play when their birthdate mandates they can't. But I'm in the "I believe people do the right thing" camp more often than not.
I know no girls on our teams are cheating. I'm sure a few are, but I hope/think it's rare.