Haggling has no point in a supermarket where the cashier's responsibility is maximizing throughout, and the streams of customers are thick.

Haggling works better at small shops with few customers and no lines. It allows the seller to have a huge markup on buyers who have little experience or time, or aren't as price-sensitive. It also allows for a human connection between the seller and a discerning buyer, and has an entertainment value for them both, like a short game.

>It allows the seller to have a huge markup on buyers who have little experience or time

Honestly, that sounds like ripping people off to me. An important part of social mobility is being able to venture into different businesses. Experience in a subject is an advantage in many dimentions, but having to learn new things while having your suppliers exploit your inexperience sounds like an unjust burden.

Nobody has little experience except tourists and they can afford it (and even with the huge markups the locally made stuff is probably cheaper than what it could be bought for in the U.S.)

It can be a waste of time when you are fleeing Roman soldiers!

How much?