Cars built today will outlast most of the old Beetles. There is a big survivorship bias at work. A percentage of them were built to slightly tighter tolerances and quality than all the others off the same line. A percentage of those will end up in the hands of owners that are meticulous about maintenance, never get in a major accident, and keep it going for decades. The handful you see left are the ones that went through several rounds of small percentage chances. There were a bajillion of those old Beetles made, so a few were bound to get through.
What cars have problems with today are things that rarely have to do with making the wheels go. They get into accidents. Their auto-dimming back windows no longer work. The GPS doesn’t get updates and thinks you’re three counties away. The engine and transmission, however, will probably go to the junkyard in perfect working order, even with shitty maintenance on the part of the owner.