It’s always nice to learn the say hello and goodbye in a few different languages. I can do French, Russian, Spanish and German.
I don’t do HF mobile, but many hams do VHF/UHF mobile using repeaters.
AND, this was a thing long long before personalized license plates were ever even imagined. My brother was a ham radio kid as a teen-ager back in the late 1950’s or early 1960’s, and his car has his call sign on the license place. It was common even then.
Personalized license places (other than that) came much later — since August 1970 in California.