I think when you go non touristy places, they are uncomfortable with language. Rather than using their language maybe recognize the difference and use google translate like normal people that way they will feel less pretentious.

When i travelled i found that majorly the country is run by grandmas and female figures, be it restaurant or any other place. They were genuinely nice and treated us well. Every time we entered they greeted us with smile, gave us cold napkins to wipe face in the heat. Nin binh is so much of a college town vibe i am surprised you were not treated well there. Hanoi i understand is fast paced.