They sure do but that don't make them bad parts.
Here is the thing, everyone makes good stuff, what you choose to export might be another thing. Quality control that goes beyond the factory matters. My suppliers send me good parts, mostly. If you find a problem a good supplier they can fix it or refund and stop stocking it. Flukes can occur but not repeatedly. I am my own quality control and usually the end users best bet.
They do make OEM parts I won't use. Better can be had most times occasionally cheaper for one reason or another. Price times service time also matters. Taiwan is known for exporting quality and many other places around the globe.