I grew up with this. Typing class (as in typewriters) forced this behavior on me and I was graded on it. It's a tough habit to break when your formative keyboard habits are suddenly wrong. It's not that easy to stop when you've been doing it that way for thirty years.
Ah, I see. For typewriters they taught us to use multiple spaces because it helps make sentence endings easier to read. Commas and periods are sometimes difficult to tell apart depending on the typewriter.
I don't have too strong opinions about the people who write like this.
But there's a special place in hell for those creating websites and apps that render those spaces instead of automatically truncating to one space like the fucking Html standard expects. They have to go out of their way to enable worse looking writing.
Not sure why the downvotes, I fully agree with you. Those html standards breaking sites should burn in hell, especially the ones that still do anchor clicks with JavaScript