The vast majority of bicycles sold in North America and Europe is manufactured in just a handful of factories in Taiwan and China, often with only minimal differences between the brands (even high-end carbon bikes). And nobody makes their own tubes for steel bikes anyway.
I don't know about Soma in particular but I really don't think what you said there differentiates them in any way from any other bike brand. If you want a sincerely "made in the USA" bike, you'll probably have to dig deeper into your pocket than a fairly mainstream company like Soma.