In many countries, you may not discriminate based on nationality, race, sex, etc. However, Thai law allows discrimination; indeed, the authorities are the number one discriminator in Thailand. If you visit a national park as a tourist, you will have to pay much more than a Thai to enter the park.
Often, you will not notice the discrimination. You will see the price for tourists in English and well-known Arabic numbers, while the much lower prices for Thais are written using Thai letters and numbers. Typically, they only use Thai numbers when they want to hide the fact that they discriminate.
The photo above is from the entrance to Doi Inthanon National Park, where you will find the highest point in Thailand. The tourist price is 300 baht for adults and 150 baht for children; the Thai prices are 50 baht and 20 baht respectively. Cars and motorcycles (30 baht and 20 baht) are the same for tourists and Thais.
Doi Inthanon National Park uses Arabic numbers, making it easier to see the discrimination. It is more difficult to see the difference, when they use Thai numbers, as in this photo from Shell Cemetery in the Krabi province. Here, the price is 10 baht for a Thai child, and 20 baht for an adult Thai.
Below, you can see the Thai numbers and the corresponding Arabic numbers.
You will also find special tourist prices at many private owned attractions, and some charge a lot more for tourists than for Thai visitors, like Phuket Zoo. At Phuket Zoo, they charge 1,500 baht for a tourist and 100 baht for a Thai. At most places, the prices will be 2-3 times higher for a tourist; Phuket Zoo is in a league of its own.
And Then Some ...
Some hotels and restaurants advertise prices without VAT and service surcharge; thus, you risk getting a surprise when you get the bill. Of course, they advertise the lower prices to make you believe they are cheaper than their competitors are.
The VAT is 7 percent, and the service surcharge is 10 percent. Actually, the service surcharge should be voluntary as it corresponds to a tip; however, many restaurants consider it mandatory.
When you check the menu at a restaurant, see if there is a text about VAT and service surcharge. You may find the text with small letters at the bottom of the menu as in the photo below.
Some restaurants mark the prices with ++; which means that they will add VAT and service surcharge. You may find the text explaining the meaning of ++ hidden on page 2, or you may find it hidden on the back of the menu. If the restaurant does not mention VAT and service charge on the menu, the prices include both.
If you bring a guest to your hotel room, you may have to pay extra as well; read more about that in the Joiner Fee article.