commercial appliances didn’t take any stand-by measures to avoid “keeping the wires warm”
Generally speaking, the amount of standby current attributable to the capacitors has historically paled in comparison to the much higher standby current of the active electronics therein. The One Watt Initiative is one such program that shed light on “vampire draw” and posed a tangible target for what standby power draw for an appliance should look like: 1 Watt.
A rather infamous example of profligate standby power was TV set-top boxes, rented from the satellite or cable TV company, at some 35 Watts. Because these weren’t owned by customers, so-called free-market principles couldn’t apply and consumers couldn’t “vote with their feet” for less power-hungry set-top boxes. And the satellite/cable TV companies didn’t care, since they weren’t the ones paying for the electricity to keep those boxes powered. Hence, a perverse scenario where power was being actively wasted.
It took both carrots (eg EnergyStar labels) and sticks (eg EU and California legislation) to make changes to this sordid situation. But to answer your question in the modern day, where standby current mostly is now kept around 1 Watt or lower, it all boils down to design tradeoffs.
For most consumer products, a physical power-switch has gone the way of the dodo. The demand is for products which can turn “off” but can start up again at a moment’s notice. Excellent electronics design could achieve low-power consumption in the milliwatts, but this often entails an entirely separate circuit and supply which is used to wake up the main circuit of the appliance. That’s extra parts and thus more that can go wrong and cause warranty claims. This is really only pursued if power consumption is paramount, such as for battery-powered devices. And even with all that effort, the power draw will never be zero.
So instead, the more common approach is to reuse the existing supply and circuitry, but try to optimize it when not in active operation. That means accepting that the power supply circuitry will have some amount of always-on draw, and that the total appliance will have a standby power draw which is deemed acceptable.
I would also be remiss if I didn’t mention the EU Directives since 2013 which mandate particular power-factor targets, which for most non-motor appliances can only be achieved with active components, ie Active Power Factor Correction (Active PFC). While not strictly addressing standby power, this would be an example of a measure undertaken to avoid the heating caused by apparent power, both locally and through the grid.
From an urban planning perspective, there are some caveats to your points:
Cut-and-cover will make shallow underground tunnels cheaper to construct in almost all cases irrespective of building in an old city center or as part of building a new city center from scratch. In fact, older pre-WW2 cities are almost ideal for cut-and-cover because the tunnels can follow the street grid, yielding a tunnel which will be near to already-built destinations, while minimizing costly curves.
Probably the worst scenario for cut-and-cover is when the surface street has unnecessary curves and detours (eg American suburban arterials). So either the tunnel follows the curve and becomes weirdly farther from major destinations, or it’s built in segments using cut-and-cover where possible and digging for the rest.
At least in America, where agricultural land at the edges of metropolitan areas is still cheap, the last 70 years do not suggest huge roads, huge offices, and huge house lead to a utopia. Instead, we just get car-dependency and sprawl, as well as dead shopping malls. The benefits of this accrued to the prior generations, who wheeled-and-dealed in speculative suburban house flipping, and saddled cities with sprawling infrastructure that the existing tax base cannot afford.
It is, until it isn’t. Greenfield development “would be short term appealing but still expensive when it comes to building everything”. It’s a rare case in America where post-WW2 greenfield housing or commercial developments pay sufficient tax to maintain the municipal services those developments require.
Look at any one municipal utility and it becomes apparent that the costs scale by length or area, but the revenue scales by businesses/households. The math doesn’t suggest we need Singapore-levels of density, but constant sprawling expansion will put American cities on the brink of bankruptcy. As it stands, regressive property tax policies result in dense neighborhoods subsidizing sprawling neighborhood, but with nothing in return except more traffic and wastewater.
Either these cities must be permitted to somehow break away from their failed and costly suburban experiments, or the costs must be internalized upon greenfield development, which might not make it cheap anymore.