> I don't know how it works today, but IIRC colorization by GNU ls(1) used to require an explicit option, --color, typically added through an alias in default interactive shell configs, rather than ls automatically enabling it by default when detecting a TTY.

It works exactly like this today. Plus, lots of software added support of NO_COLOR today.

> For example, `git` automatically invokes a pager when it detects output is to a TTY; this is endlessly frustrating to me because most of the time I'd prefer it dumped everything to the screen so I could more easily scroll using my GUI terminal window.

Set your pager to cat? That's what I personally do, never really liked this built-in convention either.