We don’t use NPT in the UK, you see some bright Brit invented the “Whitworth“ thread for about 180 years ago, and that then was developed over time When the steam industry really took off to include a Male tapered thread that would seal again a tapered or parallel female with jointing paste, later ptfe tape came along and the rest is history.
BSP is the worldwide standard for plumbing fittings and pipe threads. DIN, JIS and ISO 7 are all identical to BSP.
Good post, but we do see an awful lot of NPT on fittings now - mostly due to nothing being made here, and the kit comes in with NPT connections.