All lenses that are used and not serviced will acquire haze over time, the inner lens surfaces next to the aperture and shutter are exposed to outside air, off gassing lubricants, etc. When these were used professionally, they were serviced regularly, and these surfaces are easy to clean.
Dust/haze inside the front and back lens blocks are typically different, as these are closed units (but not typically air tight). But depending on the optical properties of the glass an lens coatings, you can get internal haze. I have rarely seen this in Zeiss lenses, but keep in mind some of these lenses are 60+ years old. Dust and water have a way to get into everything. You have no idea what an original owner exposed the equipment to.
I don't see a prevalence of haze issues compared to other brands