Yeah, I had a bad time trying to get photos at Walgreens, too... the folks at CVS actually worked with me but the photo quality was severely lacking. I ended up taking some passport photos at a Shoppers Drug Mart in Canada last time I visited. Cost me about the same as Walgreens/CVS but 1000000% better experience and quality.
As far as I know they usually only hang on to your passport for a few days. It's fairly quick. Check out that tracker that was just posted.