I have had at least 14 different Canon professional bodies and I do about 35 weddings a year...never had anything even this close happen...in fact most of my cameras by the time I sell them still look pretty minty..I
use straps and now a spider holster for carry and often set them down in less than pristine surfaces. I would
definitely complain to Canon higher ups...this should not happen this easily...I did have a mark 3 for a short
time and notice the paint is quite delicate compared to other models. You can always get that rubberized
camera armor that covers the whole camer.
I agree that Canon cameras still look pretty minty by the time I sell them (while I did not have 14 professional bodies like you, I did have/sell 6 Canon DSLR's and all of them were used in dusty desert conditions but every one of them looked good by the time I sold them).
What I don't agree though is about the MK III's "paint is quite delicate" ... while I agree that it could have been the case in the particular camera you used, but for the vast majority I do not believe that is the case.
5D MK III, 16-35/2.8 L II, 24-70/2.8 VC, 24-105/4 L IS, 70-200/2.8 L IS II, 100/2.8 L IS, 40/2.8, 50/1.4, 85/1.8, 150-500 OS, 600EX-RTx2, ST-E3-RT, Rokinon 24/3.5 T-S, D7100+18-300 VR, YN568EX, 055CXPRO4+468MGRC2, 190CXPRO4+322RC2, Gorillapod Focus+496RC2, CamRanger, B+W filters, Konova K3/31.5 etc