They should learn from CAMBODIA. Cambodian population in the US is steadily increasing every year from marriage and sponsorship from those who had settled. In return, they send home billions of dollars every year. They can also visit and buy property without any problem.
Laos do not allow to have a dual citizenship and So is Thailand.
Who say Thailand is allow their citizens to have a dual citizenship ? On what Article of Thai laws ?
A some years ago a law was passed that says a Thai national could not loose their thai citizenship, and now there's a law that would not be taken from them and they will not be asked to give it up either.
Unofficailly a Thai National simple rule of Thump with passports, if you enter a country on a passport you must leave the country with the same passport. So if a Thai has a dual citizenship with UK they will leave UK with Uk passport. and if enter Thailand on their thai passport, on leaving, they must and will leave with Thai passport...
Why thai government do the way they do ? because Thailand could benefit on this kinda thing, they're very smart by allowing their citizens to have dual citizen by passing the main law...
Some people don't know anything about thai law and they are assuming that thailand allowed their citizens to have a dual citizenship.
How do i know ? Very easy answer, becaue i have a few few thai friends that came for Schooling or live here permanently in the State...