We know for sure that there are teirs...
...it's built in to the system, so that first responders such as firefighters, paramedics, and police get first dibs on cellular service in an emergency, or indeed, exclusive use is needed, so it's hardly a stretch to believe that the operators would have the capability to depriotitise traffic they consider of less worth, and of course it's also in their interests to make sure that their higher paying customers stay happy.
Whether it's the right thing to do, especially when denying it, is another matter of course.
