bosstrabs long-term it might not be a good idea for a country like Thailand to unilaterally require covid passports, as you say it could massively hit their tourist income. They might allow people from wealthy countries where it is perceived to be under control to arrive with little issue, but restrict entry from places that are still hotspots.
It might not stop a government wanting to prevent its citizens from traveling to Thailand though.
The whole thing could get very messy and lead to some contentious political negotiations.
