The problem is not bias, but uneven representation. We can get uneven representation without bias quite easily: I've not ran your system in practical terms, but

The problem is not bias, but uneven representation. We can get uneven representation without bias quite easily: I've not ran your system in practical terms, but I'd be very surprised if, in the US, this gave you republican house majorities even when they lose the popular vote. The reason is simple: Republican voters are more dispersed geographically, so it's very hard for them to get clumped into a district where they have an overwhelming advantage. This is why plenty of people prefer to do things like maximize the chance that a voter feels well represented, or minimize the safety of incumbents, instead of going for something that leads to simple lines. Another important problem of straight lines is that it ignores the physical limitations of actual voting: Each voting location is expensive (go ask in North Carolina, where magical budget cuts make it harder to vote in areas that tend to vote democratic). inconvenient, mathematical lines will give you higher average costs to get to your own polling place, and will require more polling places, or places that have to corral different people to different booths with different options. Good luck doing that without doing everything fully digitally, which is, IMO, not necessarily a good idea.