This isn't unique to any specific region, so I would guess it has to do with density of relevant industries and individuals and the rise of e-commerce. As an example, the San Francisco Bay Area used to be full of shops like Halted, Weird Stuff, Frys (back when they were healthy, not the hollowed out shell that exists today), and Radio Shacks where you could get pretty much any component, module, or development tool that you needed as a hobbyist or small company in the hardware space. What has changed in the last decade though is you can now get access to a much broader range of parts and tools relatively quickly from Mouser, Digikey, SparkFun, Amazon, etc and an even broader set slowly from AliExpress.

There are very few places remaining where there is enough density of need in immediate parts, live debugging, or cottage industry-style production to sustain markets like the one in Shenzhen. Worse, decline in one part of the market (dev tools for examples) would result in a decline in visitors and business adjacencies that speed the decline of the other parts.

Aside from Shenzhen, I'm only aware of Akibahara (smaller and more consumer focused) and some of the markets in Seoul (one of which is smaller and consumer focused, and the other which is more machining/tooling cottage industry focused).

More likely liability and labor with those skills moving to better paying jobs.

Doing BGA rework with the right tools is pretty trivial. You can teach the average high school kid to do this stuff but it's not worth it when they could just go to college and learn circuit design or programming to create a design for a less educated technician to build. If they'd rather learn the rework, there are plenty of places that will hire them for more than what someone would pay to have their phone potentially destroyed.

I’d say this is a consequence of our outsourcing the manufacture of these products. Repairing electronics is a related skill to developing/manufacturing them. It makes sense that the economy we hire to build these products would also be best at repairing them.

I think it's a combination of factors. Vocational education has never been valued (people want college degrees), and also electronics have become cheap (and harder to fix). The country has also been slowly deindustrializing in the last decades.

I think what is happening it that it much cheaper to make something in China than to repair it locally. If you spend half the cost of a new thing to repair it, you may just buy a new thing.

Still worth it for Apple devices since they charge a ridiculous amount to fix something.