Neighbors- why do they think its ok to let their dogs piss or crap on my lawn

everyday they pass, i have 2 large pit bulls , you dont see me out walking them every morning so they can piss and crap on my neighbors lawn because that would be un - neighborly, the little old ladies , what can you do, but these old guys, they act like they own the place. fuck em , its not my first rodeo, my dogs are very competitive and shit bigger than a buffalo.