Why do dog owners on walks do this

I do not have a dog, but i walk a lot. Often, on a walk a dog owner will have the leash and dog completely closelining the sidewalk. The dog will smell my shoes and ill try and get around (sometimes having to walk onto the road) but the owner just stands there and laughs. It happens a lot. I dont understand. Are they expecting every person walking to want to pet their dog? Are they just really selfish/self centered and dont care that people want to pass them? It confuses me.