Damn, I didn't know it was illegal! I can honestly say that I have seen maybe one instance of a dog doing its business on the road since I started living here eighteen months ago. In the vast, vast majority of cases I have personally observed (at least hundreds), owners let their dogs piddle on the sidewalks.
I would love to see this law enforced and I will complain to my representative. But I would also love for dog owners to have some decency and do the right thing without enforcement actions.