In this question my real interest was the general situation around the world. But I knew that questions that are too broad are liable to be closed. So I restricted it to just the Norway/Sweden border. But I added a sentence near the end asking if there was any generally prevalent worldwide way of solving it.
The question already has answers, so I'm obviously not going to change it now, regardless, but I'm curious: Would it have been too broad if I didn't mention any specific border?
Obviously, if someone did expect a bullet point list of the policies of every country on earth, that'd be a bit much. However, questions like this are usually answerable usefully without getting into too broad territory like this:
Since you might not know whether or not there's an international standard or whether you definitely even need to look up country-specific rules, I personally believe it should be fine to ask "What's the deal with X worldwide?" even if X might vary from country to country, since these can still be answered usefully quite simply, for example:
This is actually something where there isn't one worldwide policy, it varies from country to country. For example, X country is flexible and allows [A], but Y country is strict and demands [B].
You can usually find out what a given country's policy is by [...contacting embassay/looking at government website/using web resource/etc]. A useful search term is [legal name or jargon for whatever we're talking about].
...or this...
This varies from country to country, but the vast majority of countries, including every country in [EU/NAFTA/ECOWAS/ASEAN/whatever], follow [some pattern or range].
You can usually check what a given country's policy is by [...contacting embassay/looking at government website/using web resource/etc]
After all, we're not robots who will crash, catch fire and fall over throwing an error message QUESTION EXPECTS SINGULAR ANSWER, FOUND ARRAY KEYED BY COUNTRY. We're intelligent human beings who can understand an asker's intentions, and can give a useful answer that sets someone in the right direction to solve their specific problem themselves.
Whether something does or doesn't vary from country to country is useful knowledge that experienced travellers might "just know" but an inexperienced traveller might have trouble confirming. It's therefore exactly the sort of thing where users on a travel site being helpful is helpful.
That said, from past voting behaviour, I think some of the "strict" guys tend to instinctively vote to close these questions as a reflex, so it might be best to play it safe with some exception-handling wordplay in the question, just in case it is something that varies by country.
But as a long-term policy, I don't think it's particularly useful to force users to jump through hoops like this when their intentions are already clear enough to give a good answer structured like the above. I'd vote to re-open it.
"There actually isn't just one answer to this, you have to check [X] and [Y]" is a perfectly valid, useful answer. If it goes on to include info on how to then check [X] and [Y], it's a great answer.
