Can anyone explain why the rules are so strict on dog owners allowing their dogs to do their business in public areas?

I completely agree with the rules, but the same ones do not apply to horses.

I often walk in areas on the outskirts of town where horse riders are about, and the horses often do their business on the footpaths and roads.

But the owners are not expected to clean up after them. Why is this?

Arron Williams Orchard Gardens, Hove