Scat you cat!!

If you let your cat roam the neighborhood and go to the bathroom in my yard then why can't I let my dog go do his business in your yard?

I really don't understand letting cats roam and doing their business where ever they want.  If I let my dog do that everyone would have a fit...wouldn't they?  And...I must say cat poo and pee stink pretty badly when they use your yard like a litter box!!!

Someone explain this to me...cause I just don't get it!