I don't think it's a black thing, or any particular race I think some people do it when using public grills for sanitary reasons. Also done w grilling smaller things like veggies so they don't fall through. Best ever - which I made this weekend, wrap up corn on the cob in foil w a slab or butter inside the foil and grill for 15-20. Can't even tell you the flavor in your mouth. It's amazing.
I have only seen people of color use foil. I have seen cacs throw their food directly onto a park grill or any grill.