I make a comment that says I don't think it makes sense to give discounts based on charisma.
Actually it makes a lot of sense and is realistically accurate to the real world. I do not know how many here have been to actual market places or bazaars, but these are specific places in the cities for villagers and farmers who live in the country-side to come sell their natural grown food or other thingies. I've been to plenty in Croatia, Czech Republic and Sweden.
Such people are extremely friendly and will give you a discount just for having an interesting conversation or for being nice. And if you are a regular, such lovely people will give you permanent discounts and even give you extra of their product, because they're eager to sell it.
In the game, every merchant I've seen so far fits this exact type, either refugees or small merchants just wanting to sell their stock. So I agree that things should be party-wide, it would be a good change. But Barter I find completely realistic and immersive. These are small merchants in the middle of nowhere, makes sense to barter and gain discounts.
I see where you're coming from, but I don't really agree. I think a lot of what you're talking about is just business as usual. Giving discounts to repeat customers is probably the biggest thing, and then there's the angle where the merchant makes like they're giving a discount to get the customer feeling special.
That said, I do acknowledge that, in general, not many people want to do favors for folks who are downright rude. But I think that's a special circumstance that goes beyond the basic boundaries of charisma.
Anyway. It's a game, and I accept it for what it is. If I wanted to get closer to reality, then I'd have to start questioning why these small merchants are buying hundreds of pounds of weapons and bones and skulls and endless cups and jewelry, too.
Just how many daggers and suits of leather armor can the halfling druid afford to buy? And why would he buy that many to begin with? Does he have a market for this stuff?