Bear in mind that wing anti-ice isn't used much on large airline aircraft. Setting aside the fact that it cant' be used for some of the flight (when leading edge devices are deployed), and that much of the flight is conducted in conditions too cold for icing, one needs to remember that the wings are thick enough that icing is seldom a problem, and ram air rise causes a total air temperature at the wing that's considerably colder than the free airstream. What this means is that icing is seldom a problem, especially above 300 knots.
One can't compare with car windscreens because the airliner heated wing is hot enough to vapourise the droplets upon contact, so there is no runback.
Runback is one of the chief drawbacks to a heated leading edge.