There are definitely people who solder transistors by hand still. Though most not for a living. I wonder how the venn diagram looks together with the set of people designing circuits that eventually get built by machines. Maybe not as disjoint as you first imagine.
Depending on the scale of the run and innovation of the tech, it's not unusual to see a founder digging into test-run QA issues with a multimeter and soldering iron, or perhaps a serial port and software debugger. But more often in China than the US these days, or China-US partnerships. And the hobbyist Makers and home innovators still solder together one-offs a lot, that's worldwide. Speakerbox builders do a lot of projects with a little soldering.
I dare say there are more individuals who have soldered something today than there were 100 years ago.
