Cash requires in-person exchange. To use it electronically, you’d need to participate in the formal banking sector. Many people can’t or don’t.
Instead you can take your cash to any of a large number of retailers and acquire a card that sits outside the tight credit/debit-card regulations. That card, thanks to the wide reach of various multinational corporations, has broad (and cross-border) value and is suitable for electronic exchange. All that in exchange for a small(ish) tax (the price of the card plus whatever discount the recipient/exchange applies to its face value), and less recourse if you’re scammed or you screw up somehow.
Incidentally you might be interested in @patio’s description [0] of Japanese konbini (convenience store) payments. There, your remote payee gives you a transaction number. You take that number to your local convenience store and hand them the cash to complete the otherwise-electronic transaction.
[0] https://www.bitsaboutmoney.com/archive/payments-in-japan/#:~...
Cash doesn’t require in-person exchange. Western Union is cheap. I grew up with poor family, that’s how they bummed money remotely.
> has broad (and cross-border) value
I’m wondering if this is the primary use case and that’s why I don’t really get it? I see the online aspect, but it comes with a whole other set of problems that for most cases it’s hard to imagine are easier to deal with than exchanging cash. But a way to send money across borders without any controls I can see why that might be popular. Hard to tie that back to advice the AARP should be giving though.