The Leica in Jurong does not make camera equipment. They produce surveying instruments used in building and construction. Optics are also used to make these products, but certainly not in the way our camera makes use of em. But it will also be interesting to see, went for a short stint with their headquarters in Switzerland during my industrial attachment.
The main reason why these equipment are so expensive is cos they must be assembled by hand and slowly calibrated. These instruments are extremely accurate, to the degree that our cameras don't need. Besides, there are supplementary modules like lasers, IR, etc built into them, all of which our cameras don't have. The optical part is very much simpler than that of our camera lenses, usually with only 4 or so elements. Cost come largerly for the manual labour required to calibrate these instruments, all weather tests, electronics, etc etc.