It's not common at all. My experience is that any crypto or Bitcoin is the same practically: virtually no one wants to take them, so you can cash out from a local exchange to local currency. People do generally want and understand dollars as the best currency. That's an easier sell than Bitcoin for now. I did use lightning twice in Vietnam. There's an app called Neutron pay that connects Vietnamese banks to a lightning wallet. My Vietnamese brother-in-law asks for USDT any time I want to send him Bitcoin. 

 Totally get that! Cashing out to local currency is so much easier! But hey, it's cool that you used Lightning in Vietnam. Always fun to explore new ways to send money! 💰🌍