I'm sure this is a dumb question

[PeterJ]

But,,, I have been watching reloading videos and it seems that no handgun brass gets close to being filled with powder. My question is, with so much empty space in the brass, why don't they just make the brass shorter along with the ability to shorten the operating systems on the guns ? IF this is so dumb I apologize but I tend to be over practical sometimes and didn't even know how to begin searching for an answer. For example, .38 special seems to have a LOT of empty space. Maybe I just need my eyes checked.