Before they can even pay $10 per transaction, they need to buy Bitcoins first.
The problem of the unbanked isn’t that they don’t have access to financial services, it’s that they don’t have enough money. They live paycheck-to-check, if that. There’s no point in converting what little they have to Bitcoin and paying fees on the conversion, and then more fees when spending it.
It's fees all the way down. I'm not even joking. I wanted to buy an ENS domain last week, so I put $100 CAD into an exchange (~$80USD). I abandoned the attempt because, after the fees to transfer out of the exchange to a private wallet and the fees to actually make the transaction on the blockchain, I wasn't sure if I'd have enough money. That's $80 to buy something that's supposed to be $5. I couldn't even figure out how to figure out what the damn thing would actually cost in the end.
The problem of the unbanked isn’t that they don’t have access to financial services, it’s that they don’t have enough money. They live paycheck-to-check, if that. There’s no point in converting what little they have to Bitcoin and paying fees on the conversion, and then more fees when spending it.