There are 4-12 self-checkout kiosks and the loads there tend to be smaller. So the line moves. Speed of checkout once you reach the clerk in a traditional lane, hands-down faster than self.
I've seen liquor stores that handle alcohol sales through self-checkout without friction. They don't check IDs 99% of the time, which I suspect could get them in some trouble, but instead the monitoring employee basically looks at you and makes a judgement call on your age and if you're clearly not a child they approve it before you're even done scanning.
Polish Lidl works like that. You self-checkout alcohol and some store employee gets notified. They look at you and approve remotely. If you scan alcohol first, they will likely do that before you finish checkout and there is no waiting involved.
Plus traditional is where you buy alcohol.