I think the problem is the carts. An entire cart filled with bottles and cups and liquids. In first class, you get individual service. They bring you one glass,

I think the problem is the carts. An entire cart filled with bottles and cups and liquids. In first class, you get individual service. They bring you one glass, they bring you a snack. They're not carrying a tray full. I can see how use of carts and trays during turbulence is a problem. That said, maybe switch to handing out water bottles instead of forgoing the service altogether.