[Arizhel]

Soldering? Soldering for electronics is almost all automated now, and with most electronics being surface-mount it's mostly done by stenciled solder paste and reflow. The exception is for the few remaining items that can't be done that way, such as when wires need to be soldered to PCBs (though here for high-volume stuff they usually use connectors because the wires can be assembled with connectors elsewhere, and then the wire harnesses simply plugged in during final assembly).

Are you talking about some other kind of soldering, such as for stained glass or plumbing? Stained glass with real lead and real glass is pretty rare these days, much more rare than high-quality woodwork, and mainly for hobbyists. Plumbing soldering is done with a blowtorch and isn't all that difficult, but worse, copper in plumbing is being replaced by plastic which doesn't use soldering, but rather press-fit connectors. So don't count on that as a long-lived profession either (the soldering part I mean; plumbing itself will be around as long as humans have biological bodies and need to use water for cooking, hand-washing, toilets, and bathing, it'll just be easier as new technologies replace legacy ones).

[erikb]

That is mass production you are talking about. But there are a lot of people who build their own special purpose devices, and all the alpha/beta testing happens with manually soldered hardware, since prepping a machine for just 10 boards is way too expensive. For that reason even in production many of these devices are at least partly manually assembled to save money. We are talking 1000+ devices to make machine production profitable. Many devices don't have that many customers, at least until the next set of hardware is there.

[Arizhel]

>But there are a lot of people who build their own special purpose devices,

Those are called "hobbyists".

>and all the alpha/beta testing happens with manually soldered hardware, since prepping a machine for just 10 boards is way too expensive

This is absolutely wrong. You can't manually place BGAs with any accuracy. I work in an R&D environment; our electronics are custom-built in-house at very low volumes, and they do use machines even for a one-off. Some parts can be fixed manually if they didn't get reflowed right, but BGAs cannot.

Even if you're doing boards with nothing smaller than SOICs, even there it's simpler and easier to just get a Kapton stencil and use solder paste, though you can of course pick-and-place with tweezers.