A little story from today, (not about Thai language but about Lao language, but the principle is the same - knowing a language can be useful!).
I flew from Bangkok to Luang Prabang today. I spoke Thai with the staff at Don Muang and all was good.
When I got to Luang Prabang airport, the male immigration officer was as miserable as ****, speaking curtly to every person who presented their passport. It got to my turn and I handed over my passport. He thumbed through it and then noticed many different Lao annual business visas over the past 15 years.
"Do you speak Lao?" he asked me in Lao. "Yes" I replied in Lao, "but I have to practice every day!"
His demeanour completely changed. He smiled and asked me if I had a Lao wife (and so on and so on), then asked me about my previous jobs as a teacher in Laos. All was great, his Lao immigration colleagues joked with me in Lao about getting a Lao wife, and I sailed though immigration in seconds 🙂
There is never a problem that you know too many languages.....