We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember saying something
like:

AAA batteries are almost unheard of in Europe

Rubbish.
Friends who have been in Portugal and France 10 or 15 years ago could
hardly find AAA batteries for devices they took with them. Might be
different today.

They've been absolutely common here for many years, but again, the
French market might have been different.

AAA batteries were virtually unobtanium in Zambia,
and not much better in Burkina Faso.

Back of beyond, not surprising.

AA was common - D was everywhere.
In Britland they had there own "torch" batteries that we never, or
seldom, see for sale in Canada or the US.

Oh yes, there were some oddball sizes for 6V lanterns, cycle lamps, and
the like.