Yeah, no, I'm not even talking about any kind of paranoid crap like that, see above for my reasoning not to buy their products.
Again, I used to work for a router manufacturer and we ended having to move some production from Taiwan to xina due to lack of suitable manufacturing (actually production testing) partners in Taiwan. It's not as if a factory in xina can just inject their own code into the router firmware of a random company during production, as usually pre-programmed memory chips are provided or an encrypted firmware image is provided, that is programmed during the production.
I tend to agree - most of the security issues are sloppy code, not intentional - intentional backdoors take a lot of skill to execute cleanly...
Taiwan and Shenzen - making product in Shenzen is simply amazing - much like Hinchsu Park in Taiwan - one can take a HW design done in-house, and sit down with their engineers to optimize it for manufacturing, including adjusting as needed for the supply chain...
When I say supply chain - it's everything from the plastics to the chips and all the popcorn parts like resistors, capacitors, etc - the parts that go into your router/AP benefit from Shenzhen being ground zero for the mobile/handset business - the parts are the same at a basic level... it's the economics of scale...
Sitting down with their factory guys, one can tune the board layouts and parts - this is what they do, and the factory time is the same, whether it's a 1000 units per hour, or 2000 - most of the factory/production folks want to move product as fast as possible through the lines and less hands on the product, the better...
As
@TheLostSwede mentions - the NAND/NOR/eMMC parts are usually preflashed - not just for security, but also to save time - and the code that codes in those parts is generally written outside of the factory - for my products, code was in the US, UK, DE, and India...
Things are moving about - India and Vietnam are getting market share on the factories - it takes time...
I have concerns when politics steps in - "China Bad" isn't really true, as we're all connected at the economic level, and that makes folks work together to get things done...
End of the day - if one wants to Make America Great Again and buy a US made Router/AP - are you willing to pay twice the price?
If so, speak up, and if enough of you do - maybe we can explore it...
Until then - keep in mind that every high-end smartphone is still made in... yep, China