legal – Which countries allow to work remotely on visitor visas?

You need to distinguish between “work” and “business”. Entering a country for work means that you will provide your effort to people in that country, and they will pay you, or even if they don’t pay you, they could have paid a local. Friends of mine have been turned away from the US to speak at a conference, for example, when being given an honourarium of 1/10th their actual bill rate, and even when not getting a fee, because an American could have that speaker slot and be paid.

Entering a country for business means you will continue to be paid by your foreign employer and interact with people in the country you’re visiting in some way that benefits your employer. You might learn something, negotiate a deal, tell people the status of something, etc. This is not “working” in the immigration sense of the word.

Many countries distinguish between a tourist visa and a business visa, but many others do not. They all care about work. Just as in physics, “work” here is a jargon word that has a more precise meaning than it does in general conversation.