The use of pneumatic nailers has substantially reduced the time required to frame a house.
Regarding labor costs and productivity, there is vastly more specialization in building a house now than there was in 1950. I suspect that in 1950 you only had a few types of skilled labor involved: carpenter, electrician, plumber, and maybe a flooring person (the flooring may have also been done by carpenter at that time). Now, there are additional specialties that need to be involved - roofer, concrete, HVAC, tile, countertop, appliance, etc.
Regarding labor costs and productivity, there is vastly more specialization in building a house now than there was in 1950. I suspect that in 1950 you only had a few types of skilled labor involved: carpenter, electrician, plumber, and maybe a flooring person (the flooring may have also been done by carpenter at that time). Now, there are additional specialties that need to be involved - roofer, concrete, HVAC, tile, countertop, appliance, etc.