The 1993 dishwasher listed by a trade publication has a 10-year life expectancy. The 2007 dishwasher listed by the same trade publication has a 9-year life expectancy. That's a 10% drop over 14 years, or 1.4% per year. If the argument is that a 1952 Hotpoint "used to last 50 years" than a 2017 LG should last 41. Considering it costs a third as much, I'm good with that.
This isn't really related to the dishwashers per se, and it is too early for me to be doing any sort of math, but if it's a 10% drop over 14 years (making it, if we for some reason assume it's a linear correlation, a 0.71% life expectancy drop per year), wouldn't that translate to a 60% drop over 65 years, where the 2017 LG would last for only two decades? Or are you assuming some other more true-to-life model of dishwasher lifetime degradation? Again, this isn't really about how good the actual appliances are, I am simply curious where the numbers came from because I can't seem to figure it out. [EDIT] Also, prices from the 1950s are a little fuzzy, but here is a reference to the first truly affordable home dishwasher, for $169.50 ($1,713.31 in 2017 dollars), and here is a 1959 $184.50 Kenmore dishwasher ($1,544.49 in 2017 dollars). When I look at the LG website, the two most popular models (judging by the sheer number of reviews) that they have cost $820 and $1120. So yes, it's cheaper, but not three times cheaper.