Yup, almost all pictures have to undergo PP before they are being published or uploaded. All professionals also PP their images.
One thing for sure, you can't have a full fledge Photoshop built into the camera right? If not you will need a intel processor, ram, hdd, etc and that will increase the cost significantly. Furthermore, if manufacturers do that, then Adobe and Apple will have to close shops on their processing software...
Anyway, cameras nowadays also have more built-in parameters which can help to improve the processing of the jpegs which are quite good and can be used for printing directly. However, if you want the extra edge, PP is still essential.
PS: If you do notice, when u send your photos for printing, they will also help you to do some editing before printing them out, just that they did not tell u....