I think this is all too common. As another data point to support that this practice is widespread, reports from owners who do the work themselves often seem to have a valve out of spec that requires re-shimming, but for dealer checks, it is much more rare
Certainly saw this with my last bike, about four owners did their own valves and found at least 1/3rd of them needed swapping, the first couple of guys having it done at the dealers reported they were all "in spec", the law of averages just does not stack up here, the owners have no incentive to lie about shims needing changing, whereas the dealers in question have almost certianly charged for an inspection but not undertaken it.
Even if they do charge extra for needing to change them I woul still not trust it was done, my old (now defunct) Kawasaki dealer used to have an open workshop area so you could stand at the edge of the workshop and see the guys working, you would see most bikes being serviced with the coolant drained, rocker covers removed, torque wrenches being used etc and I like that, so many just wheel the bike around the back, kick the tyres, change the oil, leave it parked for 2 hours and whack you for a large sum of cash!