The average CEO of a US company now earns 400 times that of the average worker (depending on the survey you read). The average US worker is paid $15 an hour.
A recent diatribe in our local English language rag (AM Costa Rica) has some gringo ranting about the price differences charged by a tour for gringos and local Costa Rican nationals.
Not sure if he is aware of this but the starting monthly teacher salary is about $365 or about $3 an hour and a street cop who has been around awhile will be paid a little over $600.
Yes there is discrimination here and you'll find it in every National Park - as a visitor you will pay $10 for the park and a local will pay less than $3. And in some places local kids will get in free. Costa Rica has managed to protect more than 27% of its country for national parks and reserves for future generations to enjoy. Gringo visitors can afford it (IMHO) and just remember you are indeed subsidizing the visit of some Costa Rican child who one day will try and protect the same park you are visiting today.
For more information on how the parks got started you should snag a copy of "The Quetzal and the Macaw" by David Rains Wallace.