Our dishwasher was in our house when we moved in 22 years ago. I suspect it's about 35 years old or so. I am terrified of replacing it because so many of my friends have purchased dishwashers that would drive me absolutely nuts, such as 4-hour cycles. My SIL has one that is super quiet and has no lights or signals that it's running. If you accidentally open the door before it's done, you have to start it from the beginning and run the cycle all over again. Good grief!
The reason the newer dishwashers take so long to run a cycle is the energy efficiency. I asked the tech how they could be more energy efficient if the newer machines ran twice as long as the older ones, and he said they pulse on and off, instead of being on all the time. Still doesn't make sense to me, but whatever. My son told me as long as he could keep fixing my old dishwasher, he would.