> Compare to a stovetop where there's a big heavy pot between the element and the water, and it's not in complete contact with it.

You’re describing resistive stovetops, not induction ones where the heating element is the bottom of the pot itself.

> Also often the heating element is underneath a piece of glass.

These things under the glass do not heat anything. They are there to induce some electric current in the bottom of the pan you put on top, which actually does the heating.