The problem on the show is that the amount of ammo is finite and in demand.
You keep shooting, the zombies keep coming, and sooner or later, you're screwed.
One on one, they are very easy to kill with lawn care or home repair equipment. But you don't want a lot of them around.
Oh, and there really isn't any gun control message in the show, other than maybe, "guns good."
I like the show but I agree with you on the ridiculousness of low ammo and the scarcity of guns. Maybe if the story was taking place in England then maybe that story line would fly, but not in the US and definately not in the South.
When most of the population is zombies guns would be easy to find.