Guys, as an automotive painter I see this chipping problem every week. The way I determine if there is an adheasion problem is based on the average size of the chip and the # of chips.
Opinion #1. Rocks will chip your paint. If someone shot your car with a Daisy BB gun you would expect it to chip. A stone coming from the tire in front of you is traveling at one speed and this is compounded by your forward speed. The force is enough to chip the paint esp on vertical surfaces.
Opinion #2. If the chips are very small on
average that is what I would expect to see. If they are large on average say 7mm or greater I would be concerned. This would apply for on road use.
Opinion#3 Every car with any miles on it will get stone chips. I can always tell a tailgater by the # of chips. (my girlfriend is a perfect example) Get a bottle of touch up and stay on top of it.
I would like to see macro photos with a ruler in mm next to the chip from those complaining. Also, take a piece of 3m auto masking tape and place it over your biggest chip, press it down hard then rip it off. If it pulls more paint from around the chip
(on more than one) you have a real problem.