Cars, knives and guns are all very dangerous to human life when misused but obviously one has to strike a balance between how useful they are and the potential to do harm.
Knives are extremely useful in many circumstances and while they have lethal potential, it takes a fair dint of effort and intent to do harm. So we only criminalise their possession in public, see offensive weapons vs weapons of offense.
Losing cars, without any hyperbole, would be catastrophic to modern society so despite the danger we let people drive them but we demand licenses, insurance and training.
Guns have a very few, very specific purposes and most of those involve killing things, and in the wrong hand make it very easy to take human life (even a .22 calibre sports rifle). So we restict them heavily to those who have a genuine, demonstrable need.
How is any of that unfair?