The air filter element on my nineteen year old Sierra has been replaced just once. It will go to its grave on its second air filter element. Of course the fact that I live in a relatively dust free city helps a lot.
Looking over my fifty years of owning vehicles, the progress the automotive industry has made in reliability and longevity of vehicles has been impressive. In the seventies, a typical engine needed at least a valve job by 60K miles. The service manual on the VW Beetle recommended taking the starter apart every 20K miles and doing required maintanace on its components.
In the eighties and into the nineties, mufflers every three to four years and cooling system hoses every few years was the norm.
My Sierra still has the original exhaust system and hoses. It has needed very little work over its nineteen year life.
Labour was much cheaper in the 1920s and people worked much longer hours. It was more cost effective then to have work done on your vehicle.