I am not very convinced by a common belief I have seen around me, which is that sweets and cakes truly taste better than healthier foods. I think it is one of those common psyops which is so ubiquitous that it ends up being "true" purely through momentum and by never being questioned.
I would say the real tradeoff in food is between quality and effort. Quality includes taste, but also wholesomeness, and effort includes time and price and skill to prepare. It is possible to have healthy and tasty food, but you will very likely have to make it yourself, which costs time and requires some skills, but it is also a satisfying activity so there is that as well.
Personally I never grew up with the idea that vegetables taste bad and that you need to force yourself to eat them to stay healthy. My parents are from South East Asia, so perhaps that was a huge factor, and so they simply put down vegetables on my plate and I would eat them and enjoy them, no fuss made from either side.3
I think the dessert psyop rather comes from these factors:
Most people do not want to cook, or do not even know how to cook, which creates a self-perpetuating cycle of not wanting to do the thing you’re bad because it would be embarrassing, and then never get good at it
A subtle enjoyment of drama, where choosing the unhealthy option is a form of rebellion, as lame as it is, which give some sense of agency
Food is a very common coping mechanism in the West, since it is far more socially acceptable than drugs or being alcoholic or porn or whatever. Sugar is fairly decent at calming down the emotional system in my experience
Inherited belief from others, especially parents
A way of self-justifying, by for instance saying that sugar and fat used to be rare in the wild, which is why our palate tends to enjoy them more.
While I don't necessarily disagree with the explanation in point 5), I don't think reality is as simple as that. For one, music never existed in the wild, which is where our biology evolves from, yet humans find all sorts of music beautiful. But maybe taste is different? After all, we literally are what we eat, which means that food must have a specific match with our body.
But still, my experience is that how conscious you are has a massive effect on what types of food you appreciate, and the point of this entire mini-essay is that people tend to adopt the type of beliefs that justify their existence, rather than those which are true.
People who start living life more consciously commonly report that their taste aligns with what their body enjoys, and this has been my experience as well. Soda feels somewhat nasty, crisps are nice once in a while but quickly become sickening, and that dynamic is even more true for sweets and pastry for me, and fast food is atrocious and makes my body feel awful after it. All of this suggests to me that unhealthy food is one of the many many signs of our disembodied world.
Footnotes
2 I am aware that this doesn't solve the systemic issue of teaching being an atrocious experience. But the issue being addressed here is the psychological game that people play.