It's all going the way of the double space after a period and the oxford comma.
In the days of typesetting (which I'm old enough to remember) compositors had a wide selection of spaces for practical and aesthetic purposes. Hair space, thin space, en space, em space, and so on. You can still generate those spaces using HTML code, but most people wouldn't be able to tell the difference on a computer screen, let alone a smartphone display.
The double-space convention came about with the introduction of typewriters with monospace fonts. All characters and all spaces were the same width, so one space after a full stop looked odd.
Word processors adjust spacing on the fly, as you type, so no need for two spaces.
As for the Oxford comma, I'm a devotee. It removes ambiguity. I'm also a hold-out for the Oxford Z. British English ends verbs formed from nouns and adjectives with -ise. US usage is -ize. If you assume this suffix comes from Greek, 'z' is preferable.
It could be my imagination, but wasn't there an episode of the "Inspector Morse" series in which Morse spots this non-UK usage in a letter or note?