Actually it's likely that most(all) of the resistors and LEDs are SMDs soldered using reflow or wave soldering.
Your electronics from before the 80s (and often the 90s) was soldered by a human though.
Your electronics from before the 80s (and often the 90s) was soldered by a human though.
I am capable of assembly with 402 and 603, but I can't even begin to imagine that going well on an assembly line.
(805 is somewhere around the size of small rice, 402 is half that size)
Also, I forgot to mention most processors are BGA packages AFAIK, so impossible to actually solder manually.