I wish all of that were still true. Hey, this is a tractor forum, so I cannot believe there are still people who haven't waken up to the fact that the USA threw the baby out with the bath water by farming out ALL manufacturing in the name of obscene profit. Yes, pay triple for the "name brand" machine whose weakest link (in spite of where it was assembled) is a Chinese voltage comparator the size of a tick. Yes maybe five years from now you can still get parts. Or, just as likely, you'll be in the same boat as the proud owner of the last BSA motorcycle that rolled off the line. And if that tiny, tick-sized, IC does go to smoking on you, there aren't many techs working at welding supply repair shops who can trouble-shoot to the component level. We either tell you you're Miller is not worth fixing or sell you a new control board for $1800.
I am sorry but you have several things that are not true in your statement:
1) Obscene profits - I hear this kind of thing from people who are ignorant about a certain business. When I had a hardware store, I supposedly had obscene profits according to a small number of customers. In fact, my gross profit was 22%, out of which I had payroll, rent, taxes, etc., and when everything was said and done it was about 2%. In fact, most businesses are this way with the exception of high technology companies such as Microsoft and Apple.
2) The parts used inside of a welder are all the same. No, in fact every single company that I know that engineers products (which would include all of the welders as far as I know) designs to a MTBF or lifespan of equipment. My Miller XMT304 is supposedly designed to go a minimum of 6000 hours without maintenance of any sort. I was told by MIller service that the most common part that fails on it is the fan and power switch.
Are you suggesting that all welders are engineered to the same specs, and use the same components? Just capacitors alone (which every welder has some except for the plainest transformer units) vary greatly in spec although look almost identical from the outside. Some are rated at 85 degrees C, others at 105, 125, 150, etc. And different voltages, commonly 5, 50, 75 volts, etc. So the heavier units will typically use capacitors with a higher over-rating on temperature and voltage for the design, so they won't fail as easily if the welder gets hit with a input voltage strike. Just one simple example about components that look the same but have different lifespans.
The main point is that you are satisfied with what you have because it fits your needs. If you aren't doing much welding, you would be hard pressed to put 500 hours on a welder and don't need one that goes 10,000 hours and costs much more. There is a difference in the Harbor Freight $3.99 claw hammer and my Vaughn (sorts looks similar) 16 oz claw hammer which cost me $18. That's all I am saying.
And although the EPA is trying to destroy all remaining manufacturing in the US, they haven't succeeded yet. We are not too far behind China, and there are lots of things being made in other countries such as Japan, Germany, South Korea, etc.