Why foreigners are extorted money in name of entry fees even at Unesco heritage sites in India?

I (28M Indian) recently visited Rajasthan for tourism, All the palaces and monuments have significant price for entry tickets, for citizens its ranging from 50-400 , But all foreigners tickets are starting at minimum 4x ,5x that of Indians. Why is this the case even for government operated sites?? I what visited UK few months back , I never sat this kind of ticketing system at any place, museums, grounds or anything. Anyone knows why this is the case in India?