Paul: A-base was very common here in the US until about 60 years ago (guess), but once demand beyond 100 amps became normal, things changed. I am sure that there are thousands of them still in use in older cities here, but I haven't encountered one in at least 25 years.
I know that my grandmother's house, which was built in 1952, had the original 100 amp service and had a plug-in meter, so I can't say for sure when A-base went out of style here.
I would imagine that hard-wired meters, especially located indoors would be a huge problem for non-payment disconnections.
