Where I work, when the customer wants digital photos printing, they have to accept the copyright delcaration on the front of the screen. Of course they can lie and say 'yes' but then it is more obvious later on.
Also I quickly check most digital photos before printing them and ask the customer for more infomation about the prints if I'm suspisous. Alot of them do not understand the rules, and have the opinon that because the photo is of them, then they must own it.
Another thing, is that most customers ask for help with scanning (also some do it sneakely) so if I was helping a customer, something like a huge stamp on the back of the paper would definatley draw my attention even more.
I avoid printing images if I am not sure about the copyright on them.
To conclude, it could be worth clearly and repeatedly telling your clients about the restrictions. If you explain more as well as get them to sign, then you have done your best.
Also, I work part time on minimum wage and do my work to the highest standard, and do not cut corners.
Your dedication to your job is certainly much appreciated by many hard-working photographers. I'm not trying to insinuate that
all minimum-wage workers cut corners... after all, I would like to think that I've done pretty well at many of my relatively low-paying jobs I've worked in the past... and the one that I work at now :meh:.
It's just that, in the grand scheme, people that sincerely do great work at low-paying jobs are usually in the minority.... that's all. At least, that's been my experience with countless dozens and dozens of my past co-workers at everything from department stores, to warehouses, to auto shops. And admittedly, I can't say that from time to time over the years, after taking a whole bunch of s*** from my boss and dealing with some a*****e customers... I might have... from time-to-time... just a bit... said to myself," Screw this job!"....and maybe... just maybe... that might have been reflected in my work performance on those days.