Why do we auto - subscribe to uploaded mod?

Why do I have to re-download the mod of mine after I update it and waste double internet data, first to upload all the files and then to download files that are already in my pc? Why there isn’t an option to stop downloading in progress in mod manager after I accidentally subscribe to a mod that is too large or after you make me auto subscribe to my mod? why do i have to waste internet data and time unnecessarily?
also the game keeps running in background and does not stop after a it has started. steam keeps showing it green and doesn’t quit as it says the game is running. this system is driving me mad…