why no varsity girls in sororities?

A lot to do with the time commitment. If you're an athlete and looking to advance in your sport, that'll take precedent. Greek life requires certain events and participation that can clash with a travel sports season. You'll find a few cheerleaders, but not as many as there had been 3-4 years ago.

Maybe fraternities and sororities are different in terms of events and participation. But I know there are a lot of FSU varsity athletes in fraternities and they’re active members.
Maybe the reason women athletes are not represented in sororities is because sorority recruitment is based on requiring women to come to them. They don’t go out themselves and solicit new members.
Very different than fraternities.

I think Theta Chi has a bunch of soccer and lacrosse players and they’re all active. Soccer and softball playrs would make good sorority members. My opinion.