Where they have to use Kentucky blue grass. It also goes dormant in the fall which makes it tougher to “heal” after games. That is why you see so much field turf used. Although it is better than 80s and 90s astroturf and has more cushion than grass, the polyurethane blades and sand/rubber pellets/cork are not stable and can cause unpredictable footing (and lots of ACL and MCL tears because of it). NFL stadiums like GB, Chicago, Denver and KC have the money to constantly replace sod but there are still problems. MLB artificial turf in Texas, Arizona, and and Toronto have gotten very accurate and grasslike in surface response to the ball but the players don’t make the same movement cuts on it as football players so footing problems are less pronounced.

The fields in the sunbelt stadiums are usually Bermuda and rye grass which have super dense roots and grow year round. The surfaces in Vegas and Arizona are incredible because the heat bakes the underlying dirt and sand solid. SEC stadium grass is the most amazing stuff I’ve ever seen. It’s like playing on a perfect putting green.