> It works in places where mobile connectivity infrastructure
already exists, just (presumably) not affordable enough. It is purely an economic arbitrage game, not infrastructure development.
It's worse than that. Creating a substandard product and giving it away for free destroys infrastructure development. A large mass of customers are going to take the free offering and each one who does and would otherwise have paid comes out of the budget the provider has available for expansion and upgrades.
This doesn't change whether Facebook is building their own infrastructure or leasing someone else's. If they lease existing infrastructure then they're large enough to pay wholesale rather than retail prices and the (large) difference comes out of the local provider's capital budget. If they build their own and sell below cost then it's even worse -- competitors will lose both subscribers and margins if not go out of business entirely.
Here's how I expect Aquila to work: They'll install it and drive all the local competitors out of business, and the incumbents' infrastructure will fall into disrepair or be sold for scrap. Then at some future date there will be an economic recession and Facebook accountants will wonder whether it makes sense to keep all these drones in the air to provide free access to a bunch of customers in developing countries with no money who are therefore highly undesirable to advertisers. The answer will be no.
So they'll either discontinue the project or start charging money. At that point those people will have gone from paying money for the real internet to either paying money for the fake internet, or having no access whatsoever.