Back in the 1920's and 1930's these groups were monoploistic and were called zaibatsu.
americans under occupation "demolished" those tradehouses that they would not cause thread for american companies so they would have time to catch the markets before there is competition from other countries
Also Zeiss and Voigtländer are making co-operation. Since same factory manufactures both brands they are using same parts. Zeiss and Voigtländer Canon lenses have exactly same bayonet parts. I haven't opened lenses (yet), but maybe the electronics are same also in aperture controls?