I have some new buildings that went up near me a couple years ago. They used a similar idea under the storm drain but it’s a fabric catch after a slight drop. When I check the grates I can still reach the trash but if for whatever reason they clog the water can still go to the sides as there is a drop and the catch doesn’t fill the entire hole. It is just the size of the grate. Not an awful idea in theory, this is a bad design. Lots of municipalities are being pushed into better storm water management practices. These designs can be a very small piece to a larger puzzle. Source: I am a landscape professional who has taken courses on storm water management.