I think a good robot is as capable or more capable of assembling to tight tolerances than some German 20 year old who's been out all weekend at the beer hall.
The reason why Leicas cost so much is that the company, being small, has never had the capital to invest in modern manufacturing technology. As a result, they have to pay inflated labor costs. German labor rates are among the world's highest thanks to their welfare state.
I once bought a German made computerized paper cutter. It arrived by truck in a wooden crate. After we got it off the truck onto our loading dock I noticed there was oil leaking out the bottom. Then I noticed, while the pallet skids were on the bottom of the crate where they should be, the red "up" arrows stenciled on the sides were pointing down. When we got the crate open I found the cutter upside down with the control panel smashed to bits, broken parts all over the bottom swimming in hydraulic fluid.
I called the company and they checked the other cutters in their Brooklyn, NY warehouse and guess what - they had over 100 cutters all sitting upside down in their crates!
Apparently some idot German youth either stencilled the up arrows in the wrong direction or some other idiot German youth put the pallet skids on the wrong end.
Sorry, I don't buy into the myth of German invincibility. If you want quality, buy Japanese. If you want to save money and take advantage of modern manufacturing technology, buy Japanese.
I think the quality of optics you will get out of any high end lens from any reputable manufacturer will be on a par with one another - Nikon, Leica, Zeiss, Fujinon....
You can find a lot of detailed lens tests on cloudynights.com. The winners tend to be Japanese and Zeiss. I read one test of astronomical binoculars that said Fujinons transmitted 96% of incident light; Nikons and Zeiss a bit less. Leica was at the bottom with 85%. They're all great pieces of optics, of course, but Leica is by no means at the very top.