I also noticed when visiting Scotland and England in the 70s and later in the 90-00's the receptacle outlets have all changed to meets British Standards (BS-#).
Now all are grounded and switched receptacles (outlets). Anything that plugs into these has large rectangular pins in a safety plug, where rpongs are de-energized before they are exposed, and the "hot" wire is FUSED. This wire is also color coded as brown on almost all appliances too. the neutral wire is blue IIRC. IE a lamp is fused at 3 amps, a kettle or coffee maker at 13 amps, etc.
It seems as if everywhere in the UK outlets had been replaced and the premises re-wired. This was accompanied by new wiring in thin white round cables, run along moldings and trimfeeding out of small plastic-enclosed breaker panels, usually mounted up high near the door. I bet folks had to spend a lot of sterling for those upgrades and they seemed to be found universally. Even the light switches are small square rocker switches.
In the US, many building's wired in the 1950s and early 60s lack grounded receptacles as did the "two-pin 220-volt" outlets in UK and Europe. small appliances, cords, lamps did not really have polarized two-prong plugs until recently. Our receptacle outlets were polarized (wide prong on neutral) even before they were grounded, but many extension cords and multi-taps, 3 ways, etc were NOT polarized until 20 years or so ago.
I think the US is so larger yet suburban in sheer land coverage, so overhead is the default due to its lower expense to run, visually inspect and maintain. Many more miles for sure.
Also the applicable standards are several, and not all cohesive in coverage: UL (what plugs in and to a lesser extent, outlets, wire and breakers) , National Electrical code (the receptacles, wire, raceways and breakers) and National Electrical Safety code (outdoor meters, poles, wires and transformers - even power generation)
Mostly, US has the freedom to be as el-cheapo as we want at our own personal risk -LOL. I made a 1940's era 60 amp overhead service last for 12 years. My excuse: the premesis is operated under Engineering supervision and under continuous improvement
As I added more outlets to rooms that had 1 or 2, I ran all new 12 gauge and grounded circuits. All new wire fed back to the over-sized 18-fuse panel, I still have wiring up to ceiling lights from the 1920s open "knob and tube" that is buried behind horse-hair plaster. It was 12 gauge, 6 inches apart and the rubber is still pliable and not cracking - highly unusual. The wiring was originally installed as the farmer installed lighting fed from a 32-volt generator until the Rural Electrification Association hooked all the farms up in the late 1940's.
Central AC install finally forced me to modernize to an underground pipe, a hundred feet long from the meter/main breaker on the property line, into a new 200 amp breaker panel in the basement in the old coal bin room. A new transformer was put on the pole by the power utility, which also raised my average line voltage from 114 to 124 volts, requiring me to take measures to prolong transformer and tube life in my old radios, tvs and HiFi supplies.