Most do, even Google Photos. On most services, the files you transfer count against your storage quota, so they're essentially backing up your files bit by bit.
With Google Photos, however, you have a couple options:
1) High Quality backup, which compresses the pictures a little and re-sizes anything too big to the equivalent of a 16MP picture. These back ups are very high quality and for most phones/users that don't take pictures over 16 Megapixels, it's perfectly fine. Plus, these backups don't count against your Drive quota.
2) If you would like to keep your files 'as is', you can select Original, which uploads your pictures in their original size and without further compression. This, however, will count against your Drive quota, so if you run out of space, your backup will cease to upload until you free up some of it or get more space.