1) The problem is very difficult and requires a lot of engineering resources 2) It's very hard to make money in these countries for many reasons, including sanctions or the government restricting payments (Alipay, WeChatPay, etc)
The immediate response would be: "If the problem is so difficult, how can it be solved if not be well-known, well-established providers?"
The answer is simple: the crowdsourcing power of open source combined with billions of people with a huge incentive to get around government blocking.