What about towing gliders?
Sure, all these activities need some special training and most probably a certificate/license. But they could be a way to get free flying hours, maybe not initially right after the PPL, but maybe later after some minimum hours, to KEEP a PPL or to collect hours for the professional career.
I know about some guys from the local flying clubs here (Germany) who get free hours by towing gliders, flying a parachuters drop plane or do some non-profit sightseeing trips for visitors.