I understand that the prices of these items fluctuate due to various factors, but it discourages me from ordering them because I don't want to 1. ask the price (when you're with people you don't know well it brings attention to you possibly spending more than they would on the meal, and can make you come across as a bit overly focused on price/money - could be interpreted as rude or poor manners) 2. potentially say no based on the price and deal with related social vibes that might put off + come up with a backup on the menu 3. not ask for the price at all and be handed a surprisingly large bill. Some of the times I have asked, the waiter will have to physically leave to go check the price, which is also something I want to avoid.
You might say something like "if you have to ask, you can't afford it" but I genuinely don't mind, and can easily afford, paying $50-70 on good seafood when I'm in the mood for it. Crab and lobster are some of my favorite foods, and their market price often comes in around there. So in the course of my life restaurants have probably lost out on hundreds or maybe a couple thousand in sales because of "market price". I'm not sure if this simply something most restarateurs are unaware of, it not being worth it to reprint menus or even put the market price on a blackboard somewhere, or some other psychological phenomenon I'm unaware of - maybe putting a larger price on the menu discourages most other people from ordering it or, makes other diners think the restaurant is "too expensive" even if not ordering it, or pisses diners off when they pay $X one week and come back and see it's at $X+20. Is there a canonical reason?