Well...I may live in a rather unique environment. But, dogs on leashes/harnesses when person is on a bike or skis or skateboard or scooter are pretty common. Sometimes it will be more than one dog. Off the top of my head I think the maximum I've seen is three dogs in harness.
But, car or bike, there are way too many people who drive distracted. They are in their little world and their reaction when reality comes crashing in is often not only not pretty, it is dangerous.