Tools and weapons have different weight and points of balance. A woodchopping axe is heavy and unwieldy compared to a battle axe. And spear and shield has been one of the most historically successful weapon sets of war. I don't imagine a trident functions much differently than a spear when it comes to thrusting one handed.
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As I said before, I am not defending the spear's current implementation. But much of the trident/pitchfork's awkwardness comes from having the weight at one end, whereas a spear can be designed like a javelin and thus more easily balanced.
A trident was not designed for fighting, but thrusting downward into water. Its weight inevitably falls mostly at the head, and having three points means it's going to have even more weight at that end than would a regular spear. To balance and wield it, therefore, requires grasping it more toward that end.
Weapons like axes and clubs are swung, rather than thrust. Because of the physical principle of leverage, the farther back on a handle a weapon can be grasped, the more this extra weight is advantageous. When thrust downward, the (piercing) trident benefits from the added weight, but the more the angle of the thrust must fight gravity, the more the weight is a detriment.