Colour grading made its way into photography from the film industry and they do a lot of funky things. They've done all kinds of funky things in film even in the old days when some directors effectively bleached their films before printing to get them that washed out look.
If you see and old movie with credits for Colour Timing, this is where modern colour grading started. "Colorist" was another common term used for the person doing the colour grading. Now this is all digitally. I use a tool called Magic Bullet (from Red Giant) for video work.
The difference between a colour cast and colour grading is that colour grading is done AFTER the image has been colour corrected to be neutral. The highlights, mid-tones and shadows are graded separated, usually with either colours in the same tone family or complementary colours.
As I've said before, this type of colour work represents the photographer's opinion. As we all know, opinions differ...