I think the deal with the off-brand Chinese frames is that they probably don't have the same level of quality control during and after production. While I hope and imagine the bigger names are pulling frames randomly off the production line and checking specs, and thoroughly going over finished frames before shipping, I rather imagine Workswell et al are a little less concerned---they don't lose their market share if one person gets a bad frame because the Internet is already full of stories about how their frames explode randomly. If a Giant or Trek frame failed spectacularly and caused an injury lawsuits would follow. Workswell ... would probably change its name to Working Well and carry on undisturbed.

Personally I am willing to buy one of their products, but I can understand some people's reluctance.

Your point that they are probably laid up by the same workers in the same factory as many of the name brands seems reasonable, and the idea that the workers are good at their jobs also makes sense.