Why not? Public broadcast TV stations want to be viewed, just like web radio streams!
That said, the first one I tried (a German public broadcaster) was showing a static image of “this programme is currently unavailable for legal reasons”. (I believe they do IP-based geofencing for legal/broadcasting rights reasons.)
Yeah, just because a channel is public broadcast doesn't mean some of the content it shows hasn't been commercially produced, and a license purchased for that country's geographical area only.
I've tried watching some Italian TV channels, and some content was not available for streaming. It's a common practice here. It also applies to satellite-transmitted channels, they usually don't have the license to show some movies on that version (you can only see them on the terrestrial signal).
There was a high profile court case in about 2018 where a start-up was trying to sell rebroadcasted public TV and it was ruled illegal and held up on appeal. They even tried "renting" miniature TV antennae to users with the legal theory that they never made a "copy". Sad to see it was shot down.
This is very different though: The streams are provided by the broadcasters themselves, not by somebody that receives their signal and then rebroadcasts it.
If they didn't want their content watched abroad, they would add geoblocking or authentication. Some of the ones listed on TFA actually do that for parts of their program.
You can watch NHK World from anywhere, they make it available on their website: https://www3.nhk.or.jp/nhkworld/en/live/
They show the news at the top of every hour so we check in pretty regularly.