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I wouldn't call Zeiss lenses "exceptionally well built" as described above. They are nowhere near the quality of Leica lenses which do generally have good build quality.
They're manufactured by Cosina in Japan, supposedly under Zeiss QC but the rangefinder lenses they make that mount on the Leica M bayonet cameras suffer from a well known problem called "Zeiss wobble".
I have one Zeiss lens; a 50mm/f1.5 C-Sonnar which is a modern-day reincarnation of the classic Sonnar 1,5/50 that Zeiss made for the Contax II. My copy doesn't have the wobble, and appears to be well built but most important of all it produces sublime images. And I think that's why most people buy Zeiss lenses; for the glass.
To be fair here, none of the lenses you talk about are at all the same as the lenses the OP asked about. It was Zeiss ZE, ZF lenses. And they are very different from the rangefinder lenses.
Every review of ZE/ZF that I have been reading always write about the great build of those lenses.