Consistently poor quality food
When you have a child who doesn't eat, any food is better than none. DS dietician always points out that food is just food. It doesn't have attributes such as good or bad or naughty or cheeky, it's only food, and while some may be better for our bodies than others you can run an engine on standard fuel just as well as you can on premium.
Consistency is key with processed food. Sensory issues around food often go hand in hand with control issues, someone with a neurodevelopment condition who has difficulty in navigating a world not built for them will try to exert control over the things they can control and for many this is food. DS doesn't only have sensory issues with food around tastes, textures, and colours, he also has rituals and rules around food that must be observed - for example, food must not touch other foods on the plate, specific foods are served in specific plates, he uses specific cutlery, etc.
As a PP said, a blueberry can be sweet, sour, squishy, firm, dark blue or bluish green, seeds, no seeds, and so on. A chicken dipper is the same. Every. Bloody. Time. Same colour, same taste, same size, same shape. A chicken breast is not the same as it could be a different size each time, it could be dry, moist, flakey, chewy, it might have the vein still, it might have something like garlic butter or cheese hidden inside, it could be grilled or roasted or poached all of which affect the flavour and texture. Not so a nugget. Processed food such as nuggets, as well as being consistent, also tend to be bland and for someone who doesn't like flavours that's a good thing. They also tend to be less fibrous so are softer and have a more soothing 'mouth-feel' than alternatives.