Pick and mix is mostly paying extra money to prove you cannot be trusted near twenty open tubs of sweets. You begin with a sensible plan, take four different things, then discover the bag is somehow half foam bananas and weighs enough to qualify as hand luggage.
The pricing is part of the trap. By weight sounds fair until you remember that the nice chocolate pieces are dense and the giant marshmallows are basically sweetened air. There is always one heavy thing hiding at the bottom, quietly adding several pounds to the total while you are distracted by fizzy cola bottles.
A normal bag of sweets is cheaper, sealed, and assembled by somebody who understands proportions. Pick and mix is better because it turns buying snacks into a tiny event. You get exactly the strange combination you wanted, including the one sweet everyone else dislikes and the inevitable handful selected purely because the colour looked good.
It is objectively a poor purchasing system and I hope it never disappears. Cinemas and seaside shops would feel wrong without rows of clear tubs and a paper bag that becomes worryingly expensive at the till. The bad decisions are the product. The sweets are just how they charge for them.
