I assumed that 100 GB per day was meant to be further in the future. But just imagine that: that's about 500 million Bitcoin transactions per day, which would mean mass adoption has been reached.
Or a few spammers who want to store 4k movies on-chain. With 700 MB block clearing up the mempool every 10 minutes, you could store gigabytes of movies for a nickle.
It's funny you mention that: here, it's the opposite. More and more merchants including government institutions refuse cash, and only accept card payments. We're a debit card country though, so fees are a lot less than with creditcards.
In my place, they do hate it when you're asking to pay with card for anything lower than 5€. They'll find an excuse that their POS is broken, and accept only cash for the moment.