"everybody has to be within 3 blocks of a bus stop" is a political choice. It might result in a system that is not optimal from the perspective of a different metric. If you think that different metric would serve people better, go advocate for it politically. But realize that whatever metric gets adopted will still be a political choice. There is no escaping that.

Of course, as you say in the OP, one can certainly encourage the public to use simulations based on publicly made-available data as a guide during these political discussions to convince people that a certain metric is better than others.