Uh.. H-1B visas are used to for mechanical engineers, nurses, doctors, and MBA grads all the time. The reason you don't know them is because this is a tech-focussed forum and the absolute number of these visas going to the other professions is fewer.

But graduates of top civil engineering, nursing, biology, medical, neuroscience, physics, etc programs in the country primarily use the H-1B visa for post study employment.