It can depend on where as well. Walk into quite a few larger and smaller tech companies in Silicon Valley and you might only see Macs.
I don't doubt there are companies all Mac. I am all Mac myself. I just had a guy try and refute that the Mac market share is small. It is 13% to 87%. It is small. Not claiming to understand why, but my guess is that Apple controlling policies are not compatible with most large companies. I also think the forced obsolescence and proprietary nature of Apple products is a large problem also.