The criteria is pretty simple
How many people with knowledge and money think that installing an ATM will give them profit, nothing more.
It has nothing to do with the economy or the size of the country.
For example, France has just 2 listed there while Kosovo 4....
It definitely has something to do with how friendly the country's regulations are. If the country is supportive of Bitcoin, then it is possible that companies may look at the profit motive and set up bitcoin ATMs. If not, they wouldn't want to cross the government's path. You would have very few ATMs being set up.