I used to be a math teacher, but somehow I don't know what the use of a graphing calculator is. Why do students need them compared to a basic scientific calcula

I used to be a math teacher, but somehow I don't know what the use of a graphing calculator is. Why do students need them compared to a basic scientific calculator? In one school system I taught in, you didn't even need any calculator at all for physics because we graded them entirely on their working and explanation. They didn't need to produce numerical answers. A calculus course I taught effectively didn't need calculators either, although they were allowed, but pretty much no use.