Not that I disagree, but at what level do you establish proportional representation? At the state, county, city/town/municipality, somewhere in between? Currently, I think the boundaries are drawn ad-hoc but loosely defined by population, geography, and demographics that benefit who ever is in charge of the pen.

Proportionate along what lines?

Voter parties?

The interest voters express preferences for by voting?

The interests voters idealize (they may vote pragmatically within existing rules)?

Etc., etc.

A purely algorithmic solution needs to encode preferences and how to balance them, so they need to be defined quite precisely.