Not every safety item is necessarily an extra expense due to inefficiency. The simplest example would be electrical wire. 2 lead, paper insulated aluminum wire

Not every safety item is necessarily an extra expense due to inefficiency. The simplest example would be electrical wire. 2 lead, paper insulated aluminum wire is less expensive than 3 lead PVC insulated romex, regardless of manufacturing efficiency. There's not a lot of modern AL electrical wire for price comparison, but Home Depot lists a 1000ft spool of #2 AWG USE-2 AL wire from Southwire for $0.80 / foot. The same spool from the same manufacturer in CU is $2.32 / foot. So while not a perfect comparison, if you imagine going from a 1950's 2 wire AL situation to a 2024 3 wire CU situation, you're talking a baseline price increase of over 4x with modern efficiency. And that's before you consider that modern building codes also require many more outlets and circuits than they used to. My home, built in the 70's has 3 circuits in the kitchen. 1 counter top, 1 fridge, 1 range. IIRC the modern building code is 1 circuit for every hard wired appliance, 1 for the fridge, 2 accessory circuits and a circuit for the room walls in general. If you assume a modern house with a fridge, range, dishwasher and over the range microwave/hood combo, that's 7 circuits minimum for the kitchen. So in addition to the 4x increase in wiring costs for the existing circuits, you also have a 2x increase in the number of circuits for just that room let alone outlet spacing requirements in other rooms and the like.