It would be abhorrent to let humans change the prices of goods and services based on the color of your skin, age, gender, religion, etc. However, if a computer does it, that’s apparently just fine.

For age it is common and explicit. Senior discounts for instance, and a bit less explicitly, student discounts. It feels better when it is framed as a discount, but it is equivalent to overcharging those who don't get the discount.

For the other categories, it is usually not explicit, but it definitely happens, especially when haggling is involved.