I'd agree intermediaries aren't really adding anything of value.
The problem is however, even in cases when you can produce something as cheaply in the US as in China, a Chinese seller can still beat you on price because they pay less for shipping.
Well, wouldn't the tradeoff there be time? In the past when I've ordered products from China or Korea, the tradeoff for free or $.99 shipping was that I had to wait two weeks. I do remember some shops had started keeping local warehouses for faster shipping times, so it seems like the foreign sellers are coming at it from both ways; they will ship small parcels that take awhile to arrive, or they'll send locally and eat the shipping costs.
I'm not convinced at the moment that it's the shipping alone that is causing the issue with the US sellers, especially given the limitations of the cheap shipping agreement (under 4.4 lbs I believe it said).
It means cheap items (like small plastic items etc), where the cost of manufacture is very low, even if they can be manufactured at the same cost in the US can not beat the Chinese seller because they can't compete on price.
A small domestic package just costs more than one shipped from China. So yes, it's possible they can instead compete on delivery time, and they do.
But all else being equal, it seems dumb that they can't be given access to the same pricing as Chinese sellers if they conform to the same rules (drop off at shipping hubs, labeling standards etc).
For your consumer value, sure, but it's still a quirk that you can ship something across the glove cheaper than across states. It's because you only pay China for shipping, not the US that has to deliver it inside the border.
Are there packages for which one could trade cost for time, by shipping from USA to China (or more realistically, Mexico) first and then shipping back?
Components are actually one of the three categories of things I order from China. The other two being cheap trinkets and casual clothes. China-ordered components come from the same factories anyway, trinkets are binary (they either work or don't, not much space for quality difference), and regular clothes are crappy throwaway items regardless of where you buy them.
Anything else I consider too risky. In particular, I never order consumer electronics from China (unless I explicitly go for a particular Chinese brand). The crap quality is not worth the price savings.
I'm the same way with electronic components, though I tend to buy certain often-badly-counterfeited parts (e.g. logic-level MOSFETs, TTL-to-RS-232 converters, etc.) from reputable sellers like Digi-Key since I've run into a lot of issues in the past.
For stuff like resistors, capacitors, some microcontrollers, power supplies, etc., the Chinese sellers are pretty reliable.
It depends what you're ordering. In many cases they very much don't come from the same factories. Panasonic, Rubycon capacitors on eBay are generally fake. From digikey, generally not fake (though I've heard stories of them making their way into the supply-chain there too).
Many small shipments across the ocean are costlier than one large shipment which is then distributed locally. USPS (and other national postal services across the world) will need to increase the prices for those small shipments and make profit out of it. I can only guess that in addition to this huge quantity discounts the shipments are subsidized by the Chinese government to accelerate export. US and other countries should learn from them...
Given that in my experience, Chinese shipping times are utterly random (as little as one week to as much as 2 months), I'd expect them to actually batch all those small shipments and send them regularly in bulk on ships (with the Chinese post, not sellers, doing the batching).
I'd need to see a citation of that really, or some ballpark estimates, to give it any credence.
I wouldn't necessarily expect local-to-local shipping always to be cheaper. But I'd expect there to be at least one option where you can bring a pre-labelled package to a shipping hub and get it sent at the same or lower cost.
The problem is however, even in cases when you can produce something as cheaply in the US as in China, a Chinese seller can still beat you on price because they pay less for shipping.
And that seems dumb.