These days, 15GB of photos is pretty close to nothing. If I go on a trip for a week to take pictures, I can easily shoot 50-100GB of images. (Using my full-frame DSLR, shooting in raw, average image size is over 50MB, meaning < 20 images per GB).
I don't think I'm making too many assumptions when I say RAW photos from a DSLR being uploaded to Google Photos is not anywhere near the intended use-case.
However I still agree that 15GB of photos is pretty close to nothing these days.
