From my uncle who served in Viet Nam several times and other parts of South East Asia for almost a decade:
This is another Thailand story but a very ordinary one. At Korat Royal Thai Air Force Base in 1974 bird colonels had staff cars, the rest of us whatever we could find. The Thais, seeing an opportunity, opened for business on the base selling (very) used Honda mopeds, provided repair services and sold gasoline by the pint, actually probably a half liter. A moped will run for a long time on a half liter of gas. Guys would buy a moped, ride it daily everywhere and sell it back when they rotated away.
The counter culture was bicycles. The BX did a bustling business in Japanese bikes. Most guys, me for instance, bought a bike, dutifully had the Air Police mark various parts of it stamped with an ID number--bike rustling was a big issue-- and rode it everywhere as if it was a car. After a while guys referred to their bike as their "horse." Korat was as as flat a table, being in the central highlands of interior Thailand, so a bike was ideal. The difference from mopeds was that most guys took their bike home when they rotated away, fully intending to ride it. I did. When it arrived I discovered that the seat stem had been replaced with one that was too large and driven in with a hammer. I had to use a wheel puller to extract it. Didn't matter. I never rode that bike once I got home. Eventually, I gave it to some charity when I was cleaning out the garage.