I will occasionally throw a bag in someone's trash can, but only if they are at the curb for pickup the next day.
It's less about being lazy than about the fact that if you have the dog leash in one hand and a bag of $hit in the other, you don't have a free hand to use the flashlight if needed or if you need that 2nd hand to control your dog.
No, it is specifically about you being lazy and not being a responsible dog owner or member of society. If not having a free hand is sooo hard for you then go get an LED headlamp. I use one of these when I'm out at night and they're fantastic.