For the same reason cartoon characters walk off cliffs and never fall until they look down.

You've gotta have imagination to understand the world of cartoons.

Then again Goofy has a son that attends junior high and sells newspapers for pocket money,while Pluto may very well have several children to various partners spanning from eastcoast to westcoast depending where Mickey went for holidays...it does not make sense,same species but alien lives!

Kamy stole my line! I was going to bring about the mentioning of Minnie & Mickey, along with Donald LOL.

Few people know that Goofy was actually an experiment gone bad in the Disney biogenetics lab.

Welcome to the World of Disney. They screwed everything else up, didn't they? (Seriously, how many stories did they NOT butcher??) Besides, they let Mickey and Minnie walk around topless, while Donald Duck goes around without his pants*. What's up with that? *edited for spelling.

In the wonderful world of Disney, there are different classes of dogs; the type who can stand on two legs, drive cars and own homes and the ones who are mere pets. What the significance of this? That's something you'll have to find out for yourself.