Never heard of Mercerephobia. I'm not 'afraid' per se, I'm just totally overwhelmed by the sheer amount of choices. My wife gives me very specific instructions (size, type, color..etc) and its stressful for me to meet them. I feel like I always miss or can't find at least one item. I do the vast majority of the shopping for my family. I've always chalked it up to my ADHD. I get hyper-focused on finding items and searching for the perfect one, reading labels etc. I also have no issue with store lines. I'd much rather wait in a cashier line, then do self-checkout, which seems to glitch every single time I'm using it.