An alternative possibility is that a rideshare company sees that Alice always takes the price that's offered so Alice receives the standard price, whereas Bob is price-sensitive so he receives personalized discounts on rides until the prices reach the amount that he's willing to pay.
Which is a competitive success story. It's much more profitable to avoid competition with abusive dynamic pricing and punish users for price-shopping.
This is what most airlines and hotels do, the best prices go on google flights and google hotels and the worst prices are in their own apps.