They didn't raise the price based on demand. They raised the price so that they could "discount" it and make it look like a good deal when it wasn't.
If a product is normally $10, and then it's sold as "discounted 50% for Prime Day, now only $10," that's fraudulent.
If Amazon decides to charge more and people are willing to pay it, there's nothing wrong with that. The problem is when they lie to make people think they're getting more of a deal than they are.
But that's not what they did. Their algorithms automatically raised those prices based on demand. The demand just happened to be driven by being part of prime day.
Meaning that the algorithms were raising the non-discounted prices automatically because the discounts were driving demand?
If they're going to offer discounts that compare to the original price, that original price needs to actually be an original price, not something that's being changed while the discount is still in effect. If Amazon didn't do this, they're either utterly incompetent or they're letting it happen because they know it will trick people.
If a product is normally $10, and then it's sold as "discounted 50% for Prime Day, now only $10," that's fraudulent.
If Amazon decides to charge more and people are willing to pay it, there's nothing wrong with that. The problem is when they lie to make people think they're getting more of a deal than they are.