I'm going to write a complaint letter to Toyota over the paint chipping issue. My 2015 only has 11,800 miles and I take such good care of this car. I never tailgate, I drive with caution, and stay away from semi's. I have a heaps and heaps of paint chips mostly on mt front bumper. At this rate, I'll need a paint job / bumper replacement every two years. I'm not paying 26k+ dollars for a car that's going to look like crap in three years time.
You could do what I do and drive fast enough that nobody passes you. The car will do 112 mph fairly easy. People don't believe a Prius goes that fast so most cops won't chase you. They think there Radar is screwed up.
I just got my car last month and noticed a few paint chips on the edge of the roof just above the windscreen - and one of these has started rusting. Very surprising for such a new car, although they do salt the roads a lot in winter where it came from (Northern Ireland).
I had this problem when I got mine. Only solution is a full clear 3M wrap on the entire front end bumper, full hood and fenders.
Ferrari cars from 10/ 20 years ago also chipped easy. There are so many of those with repainted front bumpers, owners just accepted this. In my experience I have found repainted panels less chip resistant than OEM and I believe this has to do with a heating process. I believe most OEMs heat/ warm the panels before paint / primer are applied. The paint drys from the inside out as opposed to repaints that dry from the outside in. Paint won't chip unless "something" hits it I'd say. OP may need a car bra or other shield. Although OP is expressing care to avoid rocks et al, something is in his travels causing chips. Or the OP's car was repainted (partial panels perhaps) and the paint is just not sticking to the primer. That is easy enough to test utilizing a coating thickness gauge. Good luck in preventing further chips!
Good luck with your letter. Our 2014 Prius does seem to "chip" a bit easier than our 1999 Montana did, but that may just be an impression because the Montana was green/beige and the Prius is white, so the chips show up more. I'm also pretty careful about following trucks, but it's difficult to avoid those pesky insects and when you're going 80+ through Texas, it doesn't take much to cause a chip. Same with sand blowing across the highway through southern Arizona and New Mexico. And it seems worse during our Feb/Mar trips to Georgia along I-10 when there are a lot of insects through Louisiana, Mississippi and northern Florida. The interesting thing is the Prius design keeps the windshield cleaner, but the frontend definitely takes a beating and after 48,000 miles of mostly cross-country highway driving, I've given up worrying about chips.