Breakfast bar. How should it have been done?
Depending on the materials, the top may be jointed to the side internally and it may be perfectly safe. If I were designing a breakfast bar, I certainly wouldn't wish to see brackets underneath but I'd find another way to fix the top securely.

You may be right; safety first especially if children are around. Why not simply lift the top hard and see if it moves? If in doubt, call a professional out.