Actually most japanese people (especially people who live in Tokyo or other megalopolis) dont know that a part of japanese eats dolphins.
People need to stop thinking that just people some people like eating a thing in a county, it doesn't mean everyone likes it there. Stop using the word 'delicacy' to describe bizarre foods. It's like calling Pig Feet a delicacy or Potato Salad a delicacy. It's not liked by everyone. It's just food that some people like
I lived in southern Chiba for a while and thought whales were pretty ordinary to be sold in supermarkets, but apparently that's not the case in the rest of the country. Never heard of or seen dolphins being sold though.