The food and drinks don’t “NEED” the dyes.

There are certain foods that we know should look a certain way. And food scientists have spent a lot of effort determining what people think is appetizing. So as foods are more and more enhanced through GMOs, or high fructose corn syrup, etc. they know the color has to stay the same.

Colas for example had that brown color from caramel syrup, or sugars cooked down until they browned. Now high fructose corn syrup is used as the sweetener and coloring is used to restore the hue.

Why some food colors are harmful is a whole other concern. Sometimes a product has unintended side effects. We see that in medicines all the time.