Those type of cabs were sometimes built here for commercial chassis but also the most common & popular style here in NZ was the Open Cab, which the NZ Post Office & Telegraph also used.
I would think with a large fleet order a company could get a good deal on a cab designed exactly how they wanted ; they were also probably more roomy & had the side window. The Ford Budd ''Phone booth'' cab is quite pokey, & although most people were not fat in those days, they may have been tallish