Let’s not forget that it was only a few years ago that the last remnants of the DC grid in New York City were shut down. The remaining DC customers had to get rectifier units installed.
Those final DC customers included high-power DC motors (easily controlled) used for elevators and similar applications.
75 years ago or so, some New York residents had to use "AC-DC" radios (with tube half-wave rectifiers that could pass DC without transformers) because of DC distribution.
That led to a now-obsolete form of jokes about AC or DC in other unrelated topics.
AC-DC radios which, as their name suggests, can operate on ac or DC mains, were widespread across North America & Europe during the 1950s/'60s, mainly, in the NA case because the manufacturers could save a few cents on power transformers.
In Europe it was mainly because of the still relatively common use of DC mains, especially in mining towns.
Looking at pre WW2 US radios, they mostly used transformers, with AC/DC much less prevalent.(radios were also quite expensive, so the relatively small cost of a power transformer was of minor concern.
In Australia, the situation was quite different, as the massive ramping up of tube construction during WW2 was all aimed at 6.3 volt & 12 volt heater types as used in the majority of military equipment.
This left the tube makers with a large inventory of such types & setting up new production lines for series string heater types was not viable, so they had to be imported.
DC mains supplies, though still not unusual, were scattered, appearing in smaller communities, the power grid was not well established, & any new installations were going to be ac.
On top of that, in Australia, radios had always been costly, transformers were relatively cheap, the Electrical regulators did not like the idea of transformerless designs in the least, so that country went for the power transformer/full wave rectifier architecture.
There are a number of advantages with such designs apart from using 6v heater tubes, such as full wave rectification requires less filtering, the mains are isolated from the chassis so you don't need elaborate insulation, you can have any HT voltage you can get transformer secondaries wound for, meaning audio output stages are capable of greater power. (this is a drawback for transformerless designs on "110v" systems, though not so much with 220/240v)