Even that would be faster if the shop moved to the "insert cash or card, or select cashback amount" method popular in the UK rather than having to tap "card", "no cashback", "full amount" first (Oz / coles)
Actually, for the fastest system I know, see London Underground. For a while now you can tap your credit card instead of the usual Oyster and you'll get close to immediate access.
This is set by the bank. In most cases you can adjust the limit. I remember Lloyds allowed you to do that.
Ok, I agree that it's a bit annoying when I have to wait a few seconds before the terminal will allow me to tap, but it's wait, what, signing?
In all seriousness, the problem you're describing is archaic terminals. Here in Canada I can't remember the last time I signed for a credit card transaction; I very rarely even have to enter my PIN. And it's much faster than paying cash.
In most places you would have done 1 and 2 while they are still scanning your items.
Then of course there are the old, slow machines that take half a minute to connect over some shitty gprs connection but those are only used by individual cloathing and jewelery merchants, not 7-11.
Cash, or android pay is way quicker. Or if you can find one a chipless credit card.