If memory serves me right certain AFSCs in the USAF banned tattoos that were visible. Some were for obvious reasons like USAF ceremonial units. Some were related to special operations where "no identifiable marks or tattoos" was specified because the member needed to be "sanitized"...
In any case I seem to remember that forearm tattoos were limited in size, number and quality then. I do remember one of my troops getting an article 15 for a tattoo of a marijuana leaf.
In any case, the culture was different and not many had tattoos.
Some tattoos were intended to make one non draftable.
It’s my recollection, as well, that visible tattoos were banned in the early 70’s.