A well aimed, correctly placed shot of the right type can be exceedingly fatal but it doesn't follow that waving any gun in the general direction of something and carelessly pulling the trigger will achieve that.
Firstly one has to get in the right position to get a good shot. Of course bad hunters could take carefree pot shots, but they would be widely condemned by their peers. The right position means you have to be:
- close enough. Many forms of hunting will take all day to carefully track an animal and if you're lucky at the end of the day take one careful shot
- from the right direction. You wouldn't take a shot from behind the animal
- able to fire safely. You wouldn't fire at an deer on top of a hill as you have to think about where the bullet will go afterwards
Some forms of hunting, like a driven bird shoot can involve just standing and waiting for birds to come in your direction then take careful shots at them. With this type of shooting I can see more resonance with your objection but hitting a moving target is easier said than done and etiquette on these considers a well execute hard shot much better than going for easy ones.
For many other forms of hunting the actual shot is a very small part of the whole activity and whatever weapon is being used makes much less difference.
Then one also has to remember that there are many different types of gun. Take for example using a large caliber rifle and distances over 1km vs hunting with a handgun. Both require huge amounts of skill in handling the weapon on top of the other general hunting skills.
Some countries require a permit to go hunting, which follows a lot of study and then an exam. This material goes into a lot of depth, and actually discharging the weapon is a surprisingly small amount of this material.
Technology-wise a gun is an improvement on exhaustion hunting, or using more primitive projectile weapons, but is far from making the whole process overwhelmingly easy.