I don’t think they even try to get work visas. A lot of countries have tourist visas up to 90 days. And if you go to a country to work there, but are not paid by a local company, you are basically a tourist.

I think this is what AirBnB are doing. A lot of countries have a requirement for you to reside in it for at least half the year to be able to be taxed there and be considered an employee. A lot of countries allow people to visit for limited time, as long as you don’t interfere with the local job market - e.g being a tourist. Those two are not in conflict and you can do what AirBnB are doing right now, without much more accounting difficulties. Though I’m not an accountant and take my words with a grain of salt.