Back in the late 60s and 70s thru the early 80s the japanese made well built cars that were (cheap) read inexpensive except forvthe crappy steel. Since their entire industry relied on importing raw materials and exporting finished vehicles. Costs are cut somewhere. Thinner steel, thinner vinyl upholstery, no galvanizing etc. The second reason for that is even though japan is an island surrounded with salt air and all that brings, their insurance rates go up as the cars age forcing them to trade them in by the 3rd year of ownership and buy another to keep their industry humming. The decent used cars are sold to 3rd world hell holes as used cars, the rest are recycled down.
They brought them here not realizing that we tend to keep vehicles longer. I remember my brother wanting a 79 lil red express when these were new and couldent afford the price tag. A 79 toyota SR5 short bed pickup cost half that, and thats what he bought. It had been rustproofed and undercoated at the dealer before he picked it up. They still only warrented it for 1 year on rust thru. In 3 years the bed had rust holes forming in it, and the chrome was peeling off the factory rear step bumper, but the engine still ran like a swiss watch. The cars and trucks they brought over were cheaply made with good drivetrains in them.
As their sheetmetal quality went up, and they developed a following of customers, the prices steadily increased.
However you are right. The american car makers thoughts in the 70s were we make cars, we are the only game in town, you "have to buy from us" , except that the japanese and germans also made cars too. These fit together better, the engines ran great, they got good gas mileage, **** didnt fall apart, or break. In other words they put some care into what they built.
They forced american companies to get better quality or die. Everything rusts though even the vaunted honduh accord.