Actually the simple paper surgical surgical team wears is to prevent any extra infection to the patient. After all, IF THEY HAVE THEIR INARDS EXPOSED, they are very vulnerable to it!
The shields are more for the protection of the medical staff, as you indicated from blood and any junk flying at them.
The thing is we do not have large wounds walking around in public from which to get sepsis. That is what skin is for.
We do have large gaping @$$#0<&$ walking around in public. Many of them holding high public office. And masks don't really work against them.