If your users are from poor countries, you'll also get pennies from ads. TAANSFL. If you have an actual community, it's more efficient to simply ask for donations.
If you read my post history, I'm a constant dissident in the "let's ban all web ads" movement exactly because I think they act as a redistribution mechanism from wealthier societies to poorer ones.
That said, if you're running a hobby site that only targets people from a poor country, the money has to come from them anyway, be it from ads or from donations. In that particular situation, why would ads bring more money than donations compared to sites targeting people from richer countries?
Another totally fair point, love to get proven wrong (:
I am from Spain where the minimum salary is around 700$ and has 40% of young people unemployment, however it's not poor compared to most other countries and the hosting cost is considered cheap.
I don't know what could they do where the hosting cost is significative. Do ad networks scale prices depending on the country served?
I think that's the ugly side of global capitalism as the answer is they shouldn't launch sites then.
Maybe they could try to join several groups to share the expenses. Any other ideas (besides advertising)?