Certain wild violets can be eaten too especially the purple ones but only the flowers and the stem, they taste very similar to lettuce. I would check before trying tame ones they could be different.
Because they need to be able to think and there has been no evidence that plants have any ability to think. They can react to their surroundings in a variety of ways but they cannot actually process any kind of information in a meaningful way.
This is a fascinating topic and plants can probably think to some small degree. However that's where I'm leaving this because I don't care to debate over this topic.
https://www.psychologytoday.com/blog/animal-emotions/201412/smarty-plants-research-shows-they-think-feel-and-learn