China is huge in area too. You don't have one billion people right across the street. Anything that is across the street is, by definition, a localized thing involving far fewer people, which you can totally have in US+CA+EU too.
Also don't forget tolls / tariffs. Building products that relies on parts from different countries (at least from/to USA) reduces the margins compared to a unified Chinese market.
Visas are a political human construct subject to change, not a immovable force of nature. The same visa keeping workers out, can always be removed or changed over night if desired to achieve the opposite effect: move masses of skilled people in. See operation paperclip.
If you look at historic locations of hyperinnovation there are bunch of different things. One of which is density of the activity and the supply chain. Imagine needing a new gearset for a robot, you roll down to Gear Set Alley looking for a used unit, you hit 4 different robot wrecking yards, explaining to 5 people along the way. They eventually point you over to machine shop that has modified an existing part into exactly what you are looking for.
You can solve in a day what might take you a day, what might take you 20 days, 3x the price and a lead time of weeks. These kinds of hyperfocused, super dense innovation zones have existed in many places across all of time.
This assumes that Gear Set Alley is near you. At >3km you'd go by car and the "meet people on the way" breaks down. At >100km you'd rather call them and miss the wrecking yards and other factories nearby.
In China, Gear Set Alley may easily be 1000km from you. Or it may be <3km from you, if you're lucky. The point is that China, taken as a whole, has no advantage over EU or US in geographical proximity. Certain regions may have that advantage, but that is totally possible in every country on earth (beyond a certain, very tiny minimum size).
This is true for the US alone, but US+Canada+EU is on the same order of magnitude, all of which prefer a more-than-zero-trust situation.