Flowers at the supermarket come wrapped in plastic sleeves, sometimes with a paper collar, sometimes in full bouquet wraps that make them look like they were arranged in the store. They were not arranged there. They arrived that way, and the wrapping is doing work that has nothing to do with making them look like a gift.
The sleeve is handling damage control in a supply chain that was built for canned goods and produce, not for something as fragile as a flower stem. Every part of how a supermarket receives and moves product is wrong for fresh cut flowers, and the packaging is compensating for that.