Dragon Ball Z is all about super-powerful dudes screaming and yelling and occasionally punching each other. I get that. But it doesn't negate the fact that handguns are so much more practical than a fistfight. You don't charge up a 9mm. You don't need a scouter to tell the power level of a .357 magnum. With guns, there's no pomp or circumstance, instead you just point and pull the trigger and get an instant result.
Then again, maybe you don't need guns when you can do this:
The absence of guns in DBZ is mostly due to the fact that everyone is capable of a super-powerful energy blast. Who needs an AK-47 when the Kamehameha is basically a Hummer-sized bullet with lock-on targeting? And yeah, regular ammo would probably bounce off of almost all of the Z Fighters, but not all of the heroes are invincible fireball machines. Some of them get stuck on Dragon Ball guard duty.
So what use is a gun against someone impervious to bullets? Look at it this way:
Technology in Dragon Ball Z is so far along that Dr. Gero was able to create self-aware, super-powerful androids that could learn, fight and even have sex with Krillin. If something like interstellar space travel is the norm, why couldn't Bulma and her dad whip up a gun that could shoot mini-Destructo Disks?
Giving the weak characters guns would level the playing field, or at least afford weaker characters some form of self-defense. It sure would beat watching Bulma cower in a cave for weeks at a time, and it'd give Yamcha something to do in between being dead and/or useless. Everybody wins with guns!
Superman Vs. Goku has been the subject of a lot of fan arguments, but there's not a lot of discussion regarding just how similar they are. Like Clark Kent, Kakarot was an alien sent to earth as a child and grew up as a paragon of virtue. Like Superman, he'll never waver in his principles, to the point that he's nice to the bad guys. He always wants a level playing field, and he doesn't want to fight dirty to win.
But unlike the Man of Steel, our boy Goku is as dumb as a brick that ate paint chips as a kid. Maybe it has something to do with the time he fell into a deep crevasse and hit his head.
Not only is Goku awful when it comes to recognizing social cues and understanding basic things like how medicine makes your body done feel good better, but he's also straight-up stupid when it comes to fighting. Not when it comes to the act itself, but when it comes to winning.
Example: Dude had Frieza dead to rights after he went Super Saiyan for the first time, but he wanted a fair fight -- so he let this guy who had just murdered Krillin power up to 100%. After Frieza was cut in half by his own attack, Goku still showed mercy. And so for a hot minute, the mass-murdering psychopath floated around as a torso before betraying his savior at the first possible chance.
Goku's stupidity goes beyond a sense of duty or honor. Anyone who watches Game of Thrones knows that doing the right thing will often get you killed -- but even Ned Stark knew when to man up and execute people.
Even at his greatest moments, Goku still manages to screw people over. Like the time Cell was about to self-destruct and destroy the earth, Goku sacrificed himself and teleported the both of them away -- but he didn't teleport them somewhere devoid of life like deep space, the sun or Ryan Seacrest's dead eyes. No, Goku transmitted himself and the exploding Cell right onto King Kai's planet.
Goku excuses himself by saying "Sorry guys, this is the only place I could think to bring him." Really? The only place you could bring the living nuclear bomb is the home planetoid of the guardian of the North Galaxy? You couldn't like, move yourself down a few miles on Snake Way?
Even if that planetoid's supergravity was needed to hold in the explosion, Goku still had plenty of time to snatch everyone and teleport away again. This moron murdered a King (and a monkey!) for absolutely no reason.