In relatively densely populated areas (I'm in the UK) I suspect that the "environmental cost" of fast deliveries is minimal to zero because the whole logistics

In relatively densely populated areas (I'm in the UK) I suspect that the "environmental cost" of fast deliveries is minimal to zero because the whole logistics chain is busy anyway. Impact starts to build up when vans/trucks have to be dispatched when load is not full yet in order to meet deadlines (assuming ICE vehicles).