Why do win drivers charge foreigners more?

Hello,
I’m a foreigner who has been living in Bangkok for long business trip. The win drivers — the local motorcycle taxi riders wearing orange vests — always charge me more money. The basic fare is 20 baht, but they take 30 baht only from me. Of course, it’s just a small amount of money, but it feels unfair.

When I asked them, “Why are you charging only me more? Do you think I won’t know because I’m a foreigner?” they simply said, “Anyway, for you it’s 30 baht.”

These people are basically the same type as meter taxi drivers, right?