alt Hacker NewsRAW gets all caps the same way TXT, JPG, CMD, SH, BAT, and etc. get all caps. That is, you are also perfectly free to say raw files, text files, JPEG files, command files, shell scripts, and batch scripts, or .txt files, .jpg files, .cmd files, .sh scripts, and .bat scripts, and not everyone uses the same convention (or even consistently a single one).
I don't really see "SH" being used instead of "sh". JPG and JPEG get the uppercase treatment because it is actually an initialism (Joint Photographic Experts Group) unlike "raw".