Two Fiats Ive had came with quite major paint and body defects, and it was left to me to notice them and get them put right. I doubt if any dealer would actually point out a paint chip to you.

It is tiny but I notice things like that specially when the touch up paint is a different yellow!!!!

as far as driling into metal pannels like the tail gate go it wont rust or cause majour paint isues that you can see anyway i now this from looking at the plates on my 10 year old cars

the major issue is the posability of drilling and/or screwing through screen wash pipes and wiring harnesses within the tail gate cos without looking you simply do not know were they are any dealer that carry out this practice are just stupid in my eyes

but saying that if it was done to my car i would still want it replacing even thou i know it's not guna rust

you might see some little trails of rust running with rain water from under the number plate not so nice