A few years ago I very nearly got punched in the face by a CFI because somebody who he regarded as "his" self fly hire customer decided to rent the aircraft which I look after. That school has since gone bust (for all the reasons standard in GA management but in their case there were a few "extras" in which he played a big part) and he has vanished, but that scenario is not untypical where aviation businesses aren't making money. I know of one flying school owner with a convinction for GBH.
Needless to say, I started to do my preflight checks extra carefully after that. It's paid off too, though I can never tell if the missing screws simply dropped out during the previous flight.
Sadly it is the reality of life of too many aircraft owners/operators that they must keep their head down otherwise they can find their hangared aircraft sitting out on the grass one morning.
From time to time one reads a story about something like this in the usual online forums. I can read these stories and I can see there is a LOT which isn't being said. I know of aircraft owners who have been absolutely appallingly treated, but they have waited for years to get a hangar place and they just keep their heads down and make do. Not everybody can come up with the cash to buy their own airfield, or their own hangar
I do freely offer lifts to people and never ask for a penny (a cup of tea maybe
) but I tend to avoid the small group of regular SFH pilots. OTOH long-term SFH pilots aren't the ones that are dropping out; there are very few of them anyway. It is the new PPLs that can do with interesting trips and one doesn't normally come across those unless one hangs around a school/club, where one can be easily accused of poaching, and it tends to require paying up the membership for nothing in return. I love flying for flying, not for hanging around flying clubs.
Obviously the conditions vary greatly between different locations. Mine is just one sample.