I have kids in daycare, and we’ve probably gone through most of them, but why is the focus on a single virus? I got laid out by influenza type A in 2022, and had to pay $175 to an urgent care to get tested for that.
Simplest answer: because due to the contagious nature of the virus there was a large economic incentive to being able to rapidly and accurately assess whether someone was sick, and because many businesses/governments had explicit rules around attending while infected with COVID. Similar resources and rules were not in place for other viruses.
Full answer: because it's a novel, actively evolving virus that poses significant health risks and is significantly more contagious than the other viruses you mentioned.
The FDA is concerned that we are stupid, so we aren't allowed to use them.
I guess it helps to not have the FDA blocking everything?