Very good question...

South Africa has a number of different QR based mobile wallets. They all used their own QR format, but it became a bad user experience as you had to match the code at the till with the user's app.

The retailer QR technology providers decided to standardise on a single QR format and require all mobile wallets to support the "universal" standard. Unfortunately, this universal standard (based on EMVco) looks nothing like a Bitcoin or Lightning invoice.