1-Site Safety – building construction is many multiples safer then it was in the 30s. You had something like 5 deaths on a building the size of the empire state building in 1930, and 20 deaths for the equivalent of 40 (+-) empire state buildings of construction in 2015. On a 1930s jobsite the foreman can tell Joe contractor to complete batshit crazy stuff. “Guys you need to pull 4 back to back shifts riveting these beams in place or you’re fired – you’re not getting paid for this because we’re behind schedule – and in case you forget you’re never going to find another job to feed your family because – you know – the great depression”. Nowadays on a union job you have to schedule and get approval for, 2 shifts of overtime subcontractors, overtime site safety inspectors, overtime controlled inspection inspectors, overtime building security, overtime hoist operator etc. On top of that you need to pull overtime work permits. All of this is at double time and potentially one of the groups might not be available or quote you some outrageous cost. So it’s harder more expensive to accelerate work nowadays, or keep schedule, compared to the 1930s because of safety related procedure and associated cost.
2-Permitting – there are inspections and permits throughout the construction process that cause delays. You can’t close a wall until your structural, mechanical, plumbing, sprinklers etc are inspected and approved – A-Z some if these inspections take 2-6 weeks. Not so much of a problem in the 1930s.
3-Size and experience of your design team. The empire state building may have had 80 architects on the architecture team in 1930s with computer aided design you might have 12 on an equivalent building – probably the same ratio for other consultants. During construction you had a bigger support team to coordinate field conditions – nowadays construction adminstratio teams are typically understaffed.
4-CYA Cover Your Ass – you screw up you get sued or you don’t get a permit sign off. Nowadays regulation and legal repercussions stops corner cutting. I doubt that a 1930s contractor would freak out about photographing 20,000 holes they filled with fire blocking.
5-Functional obsolescence/efficiency – they made things diesel back in the day – they really did – structure was overbuilt – pumps were built like tanks – there was less of a if it isn’t perfect to sixteenth of an inch it will fail mentality because things were overbuilt.
6-Economy – the darth if jobs allowed the owners to hire and push the A team.