[ahepp]

What are the reasons traditional ovens have such a wide band here? It seems like with modern technology one ought to be able to cut that down a bit. Is it just physically infeasible based on the size of the space to be heated? Or is it tremendous cost pressure for consumer goods? Or something else?

[cthalupa]

A variety of things. More space is definitely harder to heat evenly, especially without airflow coming from something like a convection oven, or keeping relative humidity very high, such as in a combi/steam oven, but a lot of it is cost pressure. If you go far enough up market to Miele, Wolf, etc., you can find ovens that will keep a much more consistent temperature.