Most camera raw image files (not RAW, since it's not an extension or a standard) are compressed, and have been for many years now. Some of them (notably the recent Sony standard ARW files, though it's a selectable option in some other brands) even use lossy compression for parts of the data. Yes, the files can take up a lot of space, but not nearly as much as a compressed 16-bit-per-channel RGB TIFF.