As a foreign visitor, you will pay 1000 Indian rupees to visit the Taj Mahal. An Indian visitor pays 40. A ticket to visit the Hermitage in St Petersburg in its entirety for one day? That's 700 rubles. A Russian citizen pays 400. It costs 120 dirhams to visit the Hassan II Mosque in Casablanca, which includes a guided tour, at the end of which the guide might suggest a tip for his laughably lightweight commentary. For Moroccans it's free. You'll also pay 200 baht to visit one of Thailand's national parks, 10 times what a Thai citizen pays.
The fact that foreign nationals pay more than residents to see exactly the same thing is an ongoing source of resentment, but is it unfair? One rationale is that foreign tourists have much higher disposable incomes than third-world locals, and therefore they should pay more.
If a citizen of India had to pay 1000 rupees to visit the Taj, or a Thai 200 baht to wander through a national park, many would be priced out of their own attractions. If you as a foreigner were to pay the local price there would be less revenue to devote to the maintenance of whatever it is you're paying to see.
On the other hand, a two-tier price system that lumps all foreign visitors into the rich bucket is not exactly fair for those nationals who are not overburdened with wealth. A Nepalese or a Sri Lankan might be unable to visit the Taj simply because they can't afford it.
There are other arguments to justify differential pricing. Since locals pay taxes on their wages, they're already contributing to the upkeep costs of their attractions. Foreign students pay far more to study in Australia and other westernised countries than Australian students, on the grounds they have not contributed taxes to support Australia's education system.
Some temples and other places of worship charge admission to non-believers but obviously not to those locals who are entering for the purpose of worship.
It can also be argued that even at the tariff foreigners pay, these attractions are worth what it costs to visit. If the Hermitage Museum or the Taj Mahal was transported to Australia, the foreigners' admission fee would be a bargain. That suggests it's locals who are getting a break because they deserve one, not that foreigners are being gouged.
But why not carry this rich-user-pays principle further? Britain in particular has a number of world-class museums and galleries that charge nothing for admission. The British Museum, the Victoria and Albert, the Science Museum, the National Gallery, the National Portrait Gallery and the Tate Modern to name just a handful.
It's the British taxpayer who cops the bill to keep these at the forefront of the world's cultural institutions, so why don't they charge? More to the point, apply the charge to non-residents only? Freedom of access to these institutions is seen as a basic British right and no doubt there would be grumbling, but possibly not very loud if it's the foreigner who takes the hip-pocket hit.
Visa fees are another charge that can vary with nationality. Australian passport holders pay a $117 visa fee to enter Chile. This is known as a reciprocity fee, equal to what Australia charges Chileans to enter. British and US passport holders pay nothing, since Chileans can enter Britain free of charge, and a visa waiver applies for entry to the USA.
Another kind of foreigner fee is that charged by Bhutan. The Tourism Council of Bhutan requires all foreign visitors to the country to pay a tariff of $US250 a night for the months of March to May and September to November. In other months the daily tariff drops to $US200.
This is often seen as nothing more than a gouge but that's not the case. Sure it's a daily fee, and there's no escape, but it covers the cost of tours, meals, hotel accommodation, and guide fees at about three-star standard while you're in the kingdom. It's perfectly feasible to travel around in Bhutan without spending another cent. If you want to elevate the experience with fancier accommodation and a private vehicle that's feasible, but you'll pay for those services at full cost on top of the daily fee.
See also: Six ways we annoy locals in Europe