It's not just buzz. It's more efficient than resistive heating and modern units have better performance in cold temps. Hence the push to promote them. The downside is that you have added complexity driving up installation costs and reliability down.
It may not be as green as pure electric can be in theory, but in large portions of this country electric isn't all that green either.
Heat pumps appear expensive to operate. Imagine running your AC year-round... that very thought makes many-a-homeowner shudder.
It's a niche, I give you that, and the plate can only be used with specific sized woks, but they exist.
I've seen induction cooktops in commercial kitchens before, maybe they were just being stupid?