Why not punish both?

Have you noticed that when someone is bit by a small dog people don't really care? But its a big deal when a bigger dog does it! I don't understand, each dog should get the same punishment. Yes, there is a difference in size and power BUT they should be trained to not do that. For example, I have gotten bitten from my Rottweiler and he was recommended to be put to sleep(hes fine, I saved him from that) but my little brother was attacked by my Terrier and was told to just shake it off. What?! So, that's basically giving sympathy to the little dog and y'all wanted to put my dog to sleep(why kill him!). In my eyes a Poodle is the same as a Pit-Bull, except Poodles wine, and Pits bark. Even though there are more serious injuries coming from a bigger dog you still have to see that the smaller one is doing the same thing and not being punished. Shake my head. Explain that because all my big puppies are being rejected over smaller puppies.