They don't need to know what a flat white means. I ask for a hot Americano with milk on the side. To me, that's a flat white.
In Chiang Rai, I occasionally have a spinach and mushroom omelet with salad on the side. 90 baht.
At the same place, the ham, cheese, tomato, onion and lettuce roll ( fresh-baked bread ) is 80 baht, the mango smoothie 70 baht. Fills me up nicely.
I'm sure Bangkok, Pattaya etc. those dishes would be much more expensive. And the coffee.