My last usage of lightning was a donation, and it took about 2 seconds since I have Alby set up in my browser. Can't remember the last time I ordered something with it, but the experience was similarly fast. The desktop experience with a wallet built into the browser is such an insanely good one, in some ways even better than using PayPal.
For offline merchants (eg: coffee shop), many business owners just don't want to deal with the accounting headache of accepting bitcoin.. But they might be more open to accepting lightning tips through a static QR!