You can find it in art history books, Wikipedia
I believe the correct answer is high relief.
When a sculpture is designed to be viewed from one side, and
protrudes dynamically from its background plane (at least half of their natural
circumference of sculpture must protrude from background plane) or is carved with
deeply incised marks is called high relief. For example, high-relief art was
made with marble by Francesco Grassia in Rome.
convenience is your answer, quick service is when you get your food fast so if you think about it the food will not always look good,have everything, and be completely safe because it was made fast.