Well that's obvious. If a dog shits the owner is standing right next to it. Unless you are a free runner it's pretty hard to follow a cat around.
I hate cats by the way.
My attitude towards dog's is very north Korean. Primarily due to the 2 scooby doo dogs who I lived next door to who barked All the time when their owners went to work. Try working at home and not getting annoyed.
Don't get me started on people who don't clear up their dog shit. Wankers.
I had exactly the same problem. New neighbours moved in and a cat decided to use my borders for a Brad Pitt. With 2 young kids I needed to nip this in the bud quick.
I bought an electronic thing off Amazon for 15 quid. 4 AA batteries and if it senses anything in a 7m range it sends out a high...