Are small dogs and cats free to misbehave and show aggression while big dogs are not is that fair?

I feel that some small dog owners and cat owners are irresponsible and lazy to discipline their dog or cat. Just because they are small they should not growl at guests or bite them or scratch them and then when I tell them their small dog or ca is vicious they make excuses for them and say how dare me say that and yell at me and blame me for getting bitten or scratch.I am a cat lover by the way and love friendly affectionate cats that love to cuddle only.