The biggest problem is that there's no quality control at the source... Even stuff done on spec has no measurable control. The manufacturers on this end that are buying on spec simply look at the cost and say... if I have to toss 10% or 20% or whatever... and it's still cheaper than buying here... so be it.
I know a guy who works in engineering at one of the more prominent auger manufacturers in Canada... and they started buying gearboxes from china a number of years ago... I think it was something like a 20% reject rate on stuff coming to them. But ask yourself... if they reject 10-20% outright.... how good are the ones that make the cut? Just good enough? Good enough for 1 year? 5 years? 20 years? Suppose they paid 50% more for a Hub City that will probably last 25 years if appropriately sized... and it adds 50 bucks to the price tag... is their name really worth that little?
Then there certainly is, as mfpoor has said... US manufacturers that do produce absolute junk, stamp the flag on it and call it good. It's done here too...