The reason you can tow gliders with a private (assuming the glider
pilot is paying some nominal fee for the tow and the pilot isn't
getting any of it) is because one of the glider associations has a
waver. Just like the ultra light association has FAA wavers.

-Robert

It's not a waiver if it is published in the FAR.

But the SSA did work with the FAA to get it published.

BT