That’s how my modern Bosch machine works: put stuff in, it comes out clean. The quality of a dishwasher’s results has little to do with whether it’s new or old, but whether it’s a good design or a bad one.
Unfortunately, as with many consumer goods, there's a weak negative correlation.
Perhaps, but I’m not
entirely convinced that’s true. There’s a certain survivor bias, in that we remember the models that lasted forever, and not the ones that failed comparatively quickly. Not to mention that a lot of old products required frequent maintenance. Consider how TV repairmen used to be a thing, one whose services were needed often enough to get to know the guy. Over time, the reliability increased a lot, and combined with the ever-falling cost of manufacture, it became uneconomical to even perform repairs, so we don’t bother designing them with repairability in mind. (I don’t necessarily agree with that approach, but here we are.)
And of course, the other thing is that even if the durability of an appliance is less than in the past, so is the price. A good friend of mine bought his first washing machine to go in his new home back in 1980. He says it was the base model and cost either $300 or $400. (I forget which number at the moment.) Around 2005 he replaced the washer, and at that point you could buy a base model washer for $300. But if you account for inflation, that’s a huge difference in price: that’d be just $127 in 1980 dollars. When we are talking about the retail price being literally around 1/3, is it actually reasonable to expect there to be no compromises in the construction?