is it really worth spending more 1.5 times its new cost for the 182?
This 182 is an extreme exception, it has been modified with amphibious floats and a reversing propeller, as well as 27 other significant modifications, including glass panel, full autopilot, several standby systems and Gomolzig exhaust. It was custom made, so it's not a fair comparison to the general fleet, but these planes are out there. I fly three different 182's and a 172 which are exceptional "rebuilds". I have certainly flown junk airplanes too, generally ferrying a customer's aircraft back for maintenance, or a "project" plane home, wondering to myself how they put up with the deficiencies, or it they even notice!
I'm in Canada, where yes, I think the larger "inertia" for GA enables a broader choice. Several of the flying clubs I know keep their 152s and 172s in beautiful condition. There are complaints backward about the club spending the money on new interiors and avionics, and the rental pilots treating them poorly, so it goes both ways. It just requires rental pilots and the airplane provider to commit together to raise the quality of airplane condition, and respect that once you get there. Not easy, I agree!
Your observations about instructors "enabling" their students flying defective aircraft is unfortunately too true. The instructor has little motivation to not fly! However, they are responsible for their candidate truly understanding "airworthy", and when to, and to not compromise! If nothing else, be observant, snag aircraft as appropriate, and maintain notes on aircraft condition, so if anything maintenance related ever happens, you have some records to support yourself with.