You vote for the representatives and the representatives decide what they think optimizes for their value function (some mix of getting elected again, what they think is best, what they think the aggregate want, etc.). Don’t like it, elect new representatives. What other way is there to do it?

In the sense that 9 people decided that abortion is legal (and then illegal) in a country of hundreds of millions: it is being decided by a small group of people who were assigned to the role of deciding. No different from the ACA being decided by a few hundred people. A repeal of all rules decided not by plebiscite (or a large fraction of voters, even) would lose us the constitution.

What a strange way of thinking. Do you ask permission before every new act or task? Things are legal by default unless some law or regulation comes up.