The Chinese are known for doing this kind of crap when proper quality control is not enforced.
Years back, assembly of the famous Pentax K1000 35mm SLR camera was moved from Japan to Hong Kong. Fine; the cameras from Hong Kong were just as well-built, though some changes such as a plastic top cover instead of chromed brass were made. Then assembly was moved to China and some more parts were made lower-priced. As long as the Pentax quality control people were in the factory, which was whenever the genuine Pentax product was being assembled, all was OK. But under contract, the Chinese were also permitted to use the same facility to build cameras for their domestic market under several different names. None carried the "Pentax" brand but they were obviously of the same mechanical design. Some even bore names like "Mingka K1000." This is a frequently-seen arrangment when the Chinese assemble goods for a well-known, legititmate company outside China. Typically this kind of production occurs in the same factory after regular hours, and it is done under "Chinese quality control."
While the Pentax-branded cameras were just fine, quality-controlled, checked and adjusted individually by Japanese and Hong Kong technicians, the Chinese off-brand domestic market production was a disaster. Critical parts in the shutter mechanism were not precisely machined so the shutter speeds were inaccurate. The gears weren't as well finished so the mechanism felt rough when it was wound. Adjustments were slapdash. But the cameras were CHEAP...in the People's Stores, less than 30% of what a real Pentax K1000 would cost.
Cheap enough, I thought, that I could afford one as a curiosity, even if it malfunctioned and became a paperweight. Once I got back to the USA I was able to fire the shutter six times and then it quit. I fix my own cameras anyway, so I dug inside this brand-new Chinese wonder, and found that one of the rubberized silk shutter curtains had come adrift from its roller shaft because some make-it-quick Chinese assembler had glued it without wiping off the oil left over from the machining operation. Glue doesn't stick well to oil!
Easy enough to fix if you've got the skill set...but even after I adjusted it, the shutter is still somewhat inaccurate though barely within Pentax specifications (real Pentax K1000, even built in China, meet their specs handily). At least it's a paperweight that now goes CLICK. The lens that came with it, however, is perfectly fine except that it's not as nicely finished as a real Pentax lens. Sharp as a tack, actually. I learned later that the glass elements were imported to China as prebuilt modules from Japan.
It is not a large leap for an American, British or other company to have goods built in China but to cut costs by using "Chinese quality control." On the other hand, Pentax established company-owned factories in the Philippines and in Vietnam, instead of continuing to do business with the Chinese.