How many tentraisers does it take to raise a tent? Well more that you can get into a conventional truck cab apparently. Hence this Freightliner crew cab.
Doors are always a big expense item for truck cab manufacturers. The cost of building a door, with all its fitments for windows and things is quite high and the demand for crew cabs is relatively low. So crew cabs generally use the same doors as regular cabs. It is always interesting to see what sheet metal contortions are required to fit them however, and there is certainly a lot of that in this particular version.