You don't keep every photo you shoot. Most of the time you shoot temporary photos like phone numbers, price tags, meal photos and etc. You know you will delete them in the future. You just need them for a short time to share or to remember something. Actually they will become trash after a while.
Trash photos stored in your cloud account like they are important. They waste your storage and data traffic. Also you waste a lot of time to pick and delete these trash photos between your valuable photos.
Just use Trash Camera to shoot these kind of trash photos. It has its own album, so they don't waste your storage, are not synced to cloud and don't waste your data traffic. You can easily empty your Trash Camera album just with a single click.