SWIFT is (a) not the only inter-bank system, and (b) is specifically for inter-bank exchanges (the "I" is for Interbank), so when a transaction is between two accounts in the same bank it doesn't need to touch SWIFT.

I have no idea how many cash transactions there are, but I think cash payments of just children's pocket money (let alone school dinner money) and even then just in the UK is by itself enough to exceed BTCs capacity.

I wonder if the Matutus in Nairobi are still cash, or if they're mostly MPESA now? Either way, they're probably also by themselves at least three times over the capacity limit for BTC.

Not that it matters much; while Lightning (and crypto) are technically intriguing, they're all fairly terrible for both practical and economic reasons. All the liquidity of shares, but with higher volatility and the fundamentals of a stock bubble.