I don't care who mowed the grass, explain the zombie scratches to me!

I confess to liking The Walking Dead.  Aside from the constant gore, the plots are interesting and so are the human interactions.  If you can get by the gore, it's a good show.

People argue about the manicured lawns that appear in some scenes, joking about bored zombies mowing grass or zombie goats and so on.

Yeah, there is that.  But what bothers me is the "Is she scratched?" paranoia.  Apparently, if you get bitten or scratched, well that's it unless it's a limb that can be immediately amputated.  You are as good as dead.   Nobody takes any chance that you might be naturally immune, either: they bash in your brains immediately.

In the process of doing that bashing, they might spatter blood and gore all over their normal contingent of microscopic cuts, or in their mouth or their eyes and ears.  There's no danger at all from that.  Even tearing open a whole torso while on your back and having a steaming pile of zombie guts land on you is of no concern.  But a zombie scratch?  Deadly!

And then there is "We're already infected - all of us".  If so, what is the danger from scratches?

I'm not the first person to ask this, of course.  I haven't heard any answers yet?