This can probably be said for most individual sports as well.
Team sports have the advantage of having everything organized for the players. There’s a coach. A season. A set schedule. Set practice times. Uniforms. Etc..
Sure, there’s still a cost to all that, but all the information is put together, and handed out to the parents. They know what to expect, what their schedule is, and then put on their uber hat and drive the kids everywhere.
That doesn’t exist in junior tennis.

www.aubonetennis.com