There’s a bit more to them than that. Door opening and closing systems, HVAC, software, etc. are high maintenance systems. When you get to the motors, trucks, etc. if you get fifty years ... you’re doing fantastic. They are not simple as you as think. If you’d ever seen one built, you’d know. There’s a huge amount of testing involved.
Metro’s big problem was choosing a manufacturer that didn’t have a long history in the business. Even with one of the biggest Bombardier (Adtranz) you’re still making a big leap of faith.
Typically that is a low margin business. Check Bombardier’s stock price pre-Adtranz and post-Adtranz if you don’t believe me. Diamler didn’t own Adtranz long before they dumped it. Metro’s management picked someone even less qualified.
It’s definitely in steady decline - I rode the Orange Line from New Carrolton to Ballston for a year, hated it - 50% of cars with broken AC in the summer (A Washington Post columnist measured 100 degrees in one - you had to immediately see if you got a blast of cold air when the door opened, and then if you didn’t try to run to another car.)
Doors didn’t open at my stop once, had to go to the next stop and come back.
I then drove for a year, hated that, and then I just moved to Ballston living in the same block as my job.
I basically will not take it at all anymore - not even to go downtown on weekends, because the trains are 19 minutes apart and I can’t stand waiting that long.
I worked for Wabtec (what started out way back in the day as Westinghouse Air Brake)
I live just outside a town that changed its name to Carnegie, so he would put his railyard here.
I am not a guru on trains but I am not ignorant of them either. Yes, light rail is a bit different, but rail is designed and built for heavy duty long term use.
With proper maintenance and occassional refurbishment, 50 years for a rail frame is not atypical. Yes, you can’t just ignore it for 50 years, but properly maintained, 50 years is not outrageous at all.