If that's true that can amount to a substantial saving. As a visitor I've been to many Thai National Parks and always paid the going farang rate. For example, on my one and only visit to Khao Yai I paid 200 baht whereas my b.f. paid a fraction of that, can't remember the exact amount. Soon after my visit the park entrance fee went up to 400 baht, although I seem to recall reading somewhere some of the park fees have since been reduced back down to sensible levels.
Regarding being stopped by the police, I always show them my International Driving Permit because this one has a mug shot of me whereas my home license doesn't. I have had to cough up the 'roadside' penalty of 200 baht but never had to go to a police station or get involved in any awkward bureaucratic stuff.
