Whoa. Is that an import/export opportunity here? In EU the prices of both are comparable.
It will probably change soon though. A lot of laws are being proposed to not add new gas hookups for new construction. Induction will have to become the higher end default for electric ranges.
They are just 3-phase because the utility demands 10+ kW loads to be 3-phase loads, and they often exceed that slightly. Check out the install guide on e.g. some IKEA built-in models, specifically regarding the wiring instructions.
And US residential does have 240V single-phase available.