Sure one can do photography well, through a normal clean and scratch-free window. I have managed to get many many excellent
pics doing just that. This
one was even taken through the prop, which is not easy. I just don't think there is a vast business opportunity for that kind of low grade work, due to the amount of competition caused by close to top-notch camera+lens equipment available for under say £2k, and it is obviously difficult or impossible (in a normal airplane) to get shots looking straight down.
I also think somebody doing that is not going to worry too much about having a CPL
