In the US cash is more convenient for paying dinner. Instead of the awkward dance of check -> put card -> bring back -> tip. You just pay it with tip, can easily round up or down a bit...
Here in Canada, the servers often will bring the card reader at the same time as they bring over the bill, because the assumption is you're likely paying with a card, either credit or debit, so why not save the extra trips entirely?
No, if we're talking only about convenience, a card wins every single time.
I don't wait for the change to come back. The change is part of (or the entirety of, depending) the tip.
What do you do when the bill+tax is 19? And with a normal tip would be 22 or 23?
And you don't have anything less than a 20 at the moment? Because, you know, that happens?
I guess in those cases I'd wait for change.
Maybe different strategies for managing cash? Which it's never even occurred to me until now that could be a thing.