If the person is doing something extra during my time in the store then I tip them.
A waitress or bartender who is keeping an eye on my drink and bringing me different things gets a tip.
The person who just hands me the bag over the counter is just simply doing the bare minimum to give me my product.
Like the person at the ice cream counter. There is only one possible gesture that can be made to transmit the cone to me.
They gotta hand it to me. That's the only physical maneuver that can be said to constitute selling me the thing.
SOHH are the handoffs of different quality. Like. Could you hand it to me in a way that I was like "Wow. That was really great". As long as you actually put it in my hand without damaging it, you can attempt the crappiest hand off you can muster.. and I don't think I'd even notice the dip in quality.