I wonder if provinces matter to anyone except those for whom it is important. Ask your average Thai money boy where he comes from and the answer will be the name of the nearest large town - Sisaket, Surin etc., not their province. I usually follow their answer up with a statement like "Oh, Isaan" or "Oh, northern Thailand" and inevitably they reply "Yes, have you been?". They may know the name of their province but it doesn't figure in their conversation as much as their region does. That be somewhat different for southerners, who usually just answer with "South" (region) when you ask them where from, rather than, say, Songkhla (province) - although I did have one southern money boy follow up with the explanation "my cock is Moslem" (he was circumcised)