I will give it a shot! Always excited to up my steak game.

If you have a toaster oven, I strongly recommend the toaster oven. They come up to temp fast, and they have a much tighter band of temperatures than an oven, which is always +15/-15 from your set temperature. Holding a tight, low temperature is all you're asking from the oven, and toaster ovens are built to do that (ironically, they fucking blow at making toast).

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?

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.