How do you haggle with algorithm that is being fed on aggregated data of who you are, how much do you make and what you did yesterday?

It is nowhere close to example you gave.

Exactly. Haggling makes sense when the two parties hav similar levels of information and agency. For entirely one sided transactions where one party has all the power such arbitrage only benefits the powerful party and it is very reasonable for us to come together and decide to make that illegal.

That's not true.

There are many conditions under which price variation allows the seller to maximize the overall amount of services/products that it sells to the largest number of people, all of whom feel like they're getting a good deal.

Should a loaf of bread cost the same thing in Malaysia as it does in the US? No. And if you required it to be such, then people in Malaysia simply wouldn't have bread, and people in the US would likely have higher prices because cutting off less-wealthy markets would reduce the economies of scale that drive overall prices.