>>21395856pork sausages need 32% or more to be referred to as pork sausages
any pork sausage with less than 32% is a banger. the distinction is the lack of meat in a legal sense. not many people these days distinguish between them at all, if they are even aware of why a banger was called a banger.
in regard to OP's image, "bangers and mash" is a cheap dinner mothers would feed their kids, would be nostalgic to people and if it said "sausage and mash", i would probably think theyre twats.
their "banger" pie might genuinely be good sausage, as you can still call a good quality sausage a banger, youd have to check with them