Totally different!
I worked in Florida in the 90s, and all the parks (and many clubs) charged out-of-state visitors (and us foreigners) more. I simply simply popped into the DMV and got a Florida ID card, and never once paid "outsider" prices again.
They didn't charge extra based on nationality/skin colour, it was simply "from out of state? Pay full price".
If Thailand employed similar standards, it wouldn't be an issue. (Any) tourists paying more than "locals", including foreigners living/working in the same province, wouldn't be a problem for me.
Thai prices should go up a little, and foreigner prices down a little, in my personal opinion. If you have a valid form of Thai ID (and are local to the attraction), you pay local price.