There seems to be a weird mental block for a lot of people. I've seen non-vegetarians be genuinely surprised to be informed that peanut butter and jelly sandwiches are vegan.
As someone with a mental hesitation (not quite a block) on food advertised as vegan, my reasoning is due to the type of food I'd expect. If it's advertised as vegan, I'm expecting food that would otherwise not be vegan that has been compromised to make the vegan version. If it's not advertised as vegan, I'm expecting food that just happens to be vegan, but is not the intended goal of the food. It's good food compared to all food vs good only compared to vegan food.
Take veggie burger patties. I've had some that were not made to resemble meat, but were just vegan ingredients in patty form, that are on par with some of the best meat burgers I've had. I've never had a veggie patty that was supposed to taste like meat that I could finish a bite of.
