One of the local NAIA coaches told me that there isn't enough players for the number of teams in college - not through lack of talent, but because the girls just stop playing.
The job of a college softball player doesn't pay that well. Many programs are not fully funded. If you sign to play in college, there's probably only a 50-50 chance that you'll ever play significantly with rosters of 20-25 players. You either won't be good enough, or you won't be willing to work hard for 2-3 years just for the possibility that you might some day. There's great sacrifice on your time whether you're a top player or not, but only a small number experience much glory or fanfare because hundreds of college teams play without people caring that much about them.
So it's takes a special player, one that really loves the game and wants to be a student-athlete. This is probably the most underrated quality of a college prospect - is she the kind of player that really wants to play in college, or does she just think she does?