The issue is the computer age has allowed gray-area-illegal pricing discrimination to be partook at unprecedented scale. McDonald’s sets a price per market not user. It’s funny you mention them though, because just look at the shenanigans with the $10 whopper sticker prices to drive people to “download the McDonald’s app”. It’s just setting up a reverse auction in disguise.

Funnily enough, that is especially not the case with the market Uber competes with, a.k.a taxis. The fare is pre-advertised and is based on distance/time. Transparent pricing that does not vary by customer was a very important aspect of traditional taxi services, to the point where you could see your fare change in real time as the ride progressed.

And yet, individual cabbies are enterprising enough to hoodwink individual passengers day-in, day-out, and it's all part of the game.

Mass consumer products generally don't discriminate per user like that.

This. B2C expectation is a fixed price, as if it was a property of the product or service, and any sudden changes need some plausible justification (like idk. import costs just went up because of a calamity, or sth.). When I go to the grocery store, I don't want to pay whatever I can individually negotiate with the seller - the hassle and resulting unpredictability has a large dollar cost on individuals' life too.

Well, generally, they tell everyone the price. In this case, they're only telling you the price, and that price might change tomorrow, or in 5 minutes, or if you move 5 blocks to the south, or if the local commuter train gets delayed, or... By how much, for each input? Who knows. Hence, the concern about the lack of transparency.

When I go to the supermarket, I get one price for bananas and my friend gets that same price. I don't pay 1 dollar while he pays 1.10. All the customers have the same pricing. This is the key difference.

If every customer has a different price, like Uber does, that opens up pandora's box. Naturally customers will start wondering about patterns and what they can do to lower their price. They might speculate if people of race X are given a slightly higher price on average, or what other physical characteristics might play a role.

Your supermarket doesn't play that game.

You may pay $1.10 and your friend pays $1.10 but gets a 10¢ discount with a coupon. It’s the same thing economically.

Not the same because coupons are public and equal opportunity. It's not like you get coupons for being white or being a man, but with Uber you could actually pay less for those things. Who knows?

Coupons often come only in certain magazines or newspapers so unless you bought said newspaper you would not know of them.

Again, this is fundamentally different because the content of those coupons are not proprietary. I think we all recognize there's a difference between a dynamic price black box and a coupon.

There have been government hearings in the US about grocery stores price-gouging over the rate of inflation. So yes?