Man, I feel this in my bones. I hit the same Kroger on 15th probably twice a week and the holdup is almost always somebody treating the scanner like it owes them money, holding up a barcode forever or bagging one item at a time like they got all day. My trick is to just watch the lanes for a second before I commit, whoever is moving fast and not staring at the screen wins, and if all four are jammed I'll just do the regular line and chill. Your point about the workers is spot on too, the same folks are still there, they're just doing different stuff now. You're not being too generous to the store, you're just being honest about what's actually slowing things down, take that with a grain of salt since it's just my two cents.

Tossed my finger and rag method out the window about a year ago and never looked back. But the $3 tool thing is a bit off. Caulk smoothing tools come in a pack of like 3 or 4 sizes for a few bucks, and one size never fits every gap. I use the back of a spoon or a plastic putty knife just as often. The real trick is cutting the tube tip at an angle and not overworking the bead.