Why is my Rain-X washer fluid causing problems on the highway?

I'm using RainX. It's not like what you've described. It works fine for me. no haze. perhaps you didn't defog your windshield at the right temperature. If using high heat to defog the windshield you''d get haze on the windshield because heat dissipates the water so fast and leave that white film on your wind shield. You should set the temperature control knob more towards the cooler side.