Worker transport

Workers should have to be transported from housing to workplaces. This would add additional challenges in terms of layout, make the factory feel more alive, and encourage building multiple towns rather than just one big one.
My idea to avoid having to granularly track workers is that buildings will have a Work Shift meter that ticks down. At 50-100% it would operate at full efficiency, at 0% it would either stop completely or slow down greatly depending on the difficulty setting. Buses or trains arriving at nearby stops refill it. Stops would have a generous AoE, but distance would cause a loss (more walking time = less work time), so there's a tradeoff between space usage and productivity.
Settlements would produce Work Shifts and could also have recreational buildings like parks or beaches to increase the amount you can stockpile, and there might also be an "Overtime" edict.

How about passenger trains

The city building aspect seems quite detached from the nice industrial logistic at this moment, especially at the early phases of the game. COI does not need to be another Workers and resources of the Soviet republic, but in the early game the city building is just "throw some potatoes to the plebs and done".
The way it might work would be industries until some distance of the city would take the the workforce from there like now, at bigger instances some passenger transport would be required (or building another housing nearby).

WR:SR style worker management would definitely be a bit much for CoI, but yeah i agree that the city building is quite detached from industry right now and feels a bit tacked on for a lack of a better term
I agree with Mrakomor in that a good simplified enough implementation would be that workers can get to workplaces in a range, but need transport (buses or trains?) to get to further away buildings; maybe with transport stops having a similar range and acting as "proxies" for the settlement
Could even be expanded to the settlement building itself, with residential buildings being individual buildings instead of large blocks, which just need services in a radius (and a plumbing connection); the fact that you can't have gaps in your settlement feels a bit clunky with the current system and this would fix that