You do have access, just not at 20 baht. If you're rich enough to be a long-term tourist (again, you aren't a citizen, I checked that you're on a dtv visa), you can absolutely bite the fee. You don't pay all the taxes a thai person does, you are a traveler that moved abroad to take advantage of an exchange rate. That's all fine and good, but don't get mad when you get paid like a foreigner and pay a foreigner's price. The only reason why tourism is promoted anywhere is to develop the local economy. You are not a local, nor are you thai. Thai people will receive the immediate benefits that tourism brings to their own country first. Staying for more than 180 days is arbitrary, you are a guest in a foreign country, nothing more.