There weren’t generations between the collapse and the film. Style of the old characters may have started off in “normal” civilization. Given how many cars ther

There weren’t generations between the collapse and the film. Style of the old characters may have started off in “normal” civilization. Given how many cars there are today, how the cars in mad Max tend to be simpler/older cars and how everything is Frankensteined together, the technology seems plausible. Compare to Cuba, where people are still driving around in 60 year old classic American cars. Also consider how many people live now and their resources and assets, compared to the world of mad Max, where perhaps 1% of the humans remain. It implies a lot of junk.