That's because there are 3 dates for a file - created date, modified date and accessed date, and most programs use the modified date - which is not the created date (which is the installation date). With pictures taken by camera, though, there's an EXIF (exchangeable image file format) header that has the date the picture was taken on - and programs that can set any or all of the file dates to that EXIF date (and some of them can do it to all the files in a folder in one shot, skipping the ones with no "taken on" date).
As far as root, I believe that the GPL requires that be supplied, but since no one's challenged it in court yet ... (we just use phones with unlockable bootloaders and install Magisk).