Some platforms actually do account for this by having special "developing countries" discounts, or some other euphemism like that. IIRC Gumroad is one that supports this.
Part of the difficulty in doing this at early stage (without VC) is that your costs often don't scale in proportion to customer ability to pay.
A big chunk of the costs of running Kagi will come from external search indexes - their founder is active here and was pretty open about the impacts on costs when Bing raised their API pricing significantly. That's just one player in the market, but when Bing raises their prices, they don't offer discounts to make it cheaper for developing countries for users downstream.
With investment or a significant customer base in full-price countries, it's easier to subsidize a lower price model for developing markets. Trouble is, businesses like Kagi aren't in the business of getting eyeballs today for future monetization (which works fine as justification to grow user stats if someone else is footing the server bills, and is willing to buy future growth).
It's certainly an imperfect setup, but regional pricing seems an interesting challenge to make work without relying on external investment.
I think most people have a negative kneejerk reaction to asymmetrical pricing when they're the ones paying more. Generally for most things, the cost of delivering a product or service doesn't vary too much based on factors like local living wages, so at the end of the day, you're paying more margin than some other people are. In some cases, maybe your group is flat-out subsidizing other groups.
It does seem people's opinions on this are cultural and situational, though. Like many people do not feel particularly upset by a veteran or senior discount. But for textbooks, I think most people feel like the massive margins publishers push are already unreasonable and thus the existence of asymmetric pricing is actually evidence that the margins are larger than necessary.
Not sure, though. Most practices that involve some form of discrimination are bound to be controversial in some way. (Even describing them using the term 'discrimination' is sometimes controversial due to the connotations that the word carries, but alas.)
Some people will even go out of their way to abuse a pricing scheme to get things for far cheaper. See cdkeys selling Xbox live cards from Argentina, for example