To be honest I am not attracted by these colours. They aren't bright and do not look natural. If you would show me broccoli or strawberries with whipped cream, tiramisu or French carrots I would take a bite.
To me what you show doesn't look tasty, most likely not even natural colors are used like from beets, tea, certain fruits. With a bit of a smell for sure the chemicals can be smelled. Not even my children would like to try this or say it looks attractive.

Synthetic food already sounds yech to me.

I agree with you there are plenty of other coloring options if we like to dye at all. Homemade syruos (fruits) are perfect.

The main reason today is that chemicals is what we 'all' are used to. Even homecooked meals are prepared from packages and with help of chemicals because we have the idea it lets whatever we prepare look better. Better as similar to what we buy in supermarkets prepared in factories. The reality is homebaked and cooked always looks and tastes different. I would say way better.

A plus is that without chemicals taste and smell increases and you'll find out that all you taste is salt, sugar or a strange chemical aftertaste.
Factory food is not the best food, it's addictive, unhealthy and it has a typical smell just like food prepared with the cancer inducing palm fat and trans fat.

For purple we never use purple cabbage (it can be bought in jars)/but beetroot. The root and leaves can be used. The leaves make a great lettuce as well.

Stay healthy and blessed be
🍀❤️