If you believe the word hobby is a reasonable one to use, then consider who would be to blame in the following circumstances:
1. When I'm out riding my motorcycle for pleasure, albeit responsibly and below the speed limit, a child minces out in front of me and the bike collides with her. The child is above the age when all other children have received road and vehicle awareness education.
I do ride my motorbike for pleasure and part of the blame would be mine. There is no escape from that fact however much you might want to duck it.
However this is not an analagous situation. The vast majority of traffic is people going about their livelyhoods and is therefore not a hobby. This warrents that kids should be aware of traffic as an environmental hazard. The fact that the particular journey you were taking had no specific purpose doesn't change that.
2. I'm baking some cakes that have no nutritional value whatsoever, when a friend's 4 year-old child walks in and leans on the immensely hot oven door.
Again, a large part of the responsibility would be mine. If I knew the 4 year old was around I would know he was at risk and take steps to prevent injury. I don't beleive in playing hot-potato with responsibility. I accept it.
However again the situation is not analagous. We need to eat. Food needs to be cooked. Just because in this instance the cooking is frivolous doesn't mean the child should not be aware of the dangers of hot cookers as a class as they are another unavoidable hazzard of life.
How is owning a pet dog an unavoidable hazzard of life?
Lets think ,
1. Guide dogs for the blind
2. Drugs Enforcement officers
3. Police dogs
4. ermm....
Unless you in one of these classes then I class your dog ownership as a hobby, as is the vast majority.
p.s. in places where there are wild dogs, how often are they recorded as attacking humans? Most wild animals learn very quickly to give humans a wide berth.
p.p.s this was not a rhetorical question...