Presumably it's a throughput & latency optimization. Doc only has to see you once if they already have the x-ray, instead of ordering an x-ray and then seeing y

Presumably it's a throughput & latency optimization. Doc only has to see you once if they already have the x-ray, instead of ordering an x-ray and then seeing you again. We speculatively do things in computers all the time in the name of speed & efficiency. If it cost nothing and the radiation carried no risk, nobody would have any problem with it. As it is, the cost is modest and the risk is low, so presumably healthcare waved their hands and said "close enough". (That said I still decline pre-appointment x-rays when I do not believe they are appropriate)