Electric typewriters were pretty widespread by the 60-70s or so it’s just that they don’t have quite as much “retro” appeal these days ( eg like cassettes vs vinyl)
I saw plenty of mechanical typewriters by the 80s/90s, when I learned typing at school. A relative of mine also taught a typewriter course, with several different mechanical typewriter models. Everyone I know who had a typewriter had a mechanical one. I don't think I've ever seen an electric typewriter in person; I've only read about them in the Internet. They don't seem to have been that widespread to me.