It's not that Chinese CAN'T do quality, it's that companies go to them for cheap bulk manufacturing rather than quality.
Oh, and they do need to be supervised pretty closely, so that they don't make substitutions or cut corners. Not to mention the fact that anything that's produced there will immediately be reverse-engineered and the design stolen.

As above, that hasn't been my experience with Chinese products that I've encountered. I didn't mention it, but a DIY 48V 1000w kit has an incredibly strong, quiet motor and equally excellent components as well as the many bikes I've assembled for friends and family.

Before I concealed the wiring. The rear wheel weighed 18 pounds and the entire bike (without battery) 35 pounds with lots of bling.

Very true...my brother in law has two ebikes that started as used mountain bikes he got at a yard sale. He bought two Bafang conversion kits and has been riding them for years without a single problem.
He does maintain them and takes care of them...he doesn't ride them like he stole them...this makes a big difference especially the maintaining them part.

The Chinese make what you spec...you want cheap crap that won't last you can get that, they don't really care...or you want quality and you get it because it is what you are willing to pay for the product you want to sell. Likely the competition in China is also very aggressive and the manufacturer that does a better job gets the most business and that is what it's all about in the end...making money

But don't expect that $500 internet ebike to be the same as a $1000 ebike...the more costly uses higher quality parts and is manufactured to a higher standard...Like I said in my earlier post, I get them in my shop every day and you can tell the bikes that are cared for from the ones that aren't and you can see the differences between the quality of the bikes parts, etc.