I recon the majority of english speakers will not think of the Greek word for anus. Especially educated English speakers who have had exams proctored before.
Isn't that a measure of how often words are searched? Everyone knows what a proctologist is, and no one wants to learn any more about them than they absolutely have to learn. A comedic trope is for a sadistic doctor to brutally thrust his hand into a nitrile glove and ask if some poor sap is ready for his exam. On the other hand, those with college degrees (a minority of the population) have heard the word "proctor" on eight different occasions in their entire lives.
I think the majority of English speakers are completely unaware of this meaning. “Proctor” on the other hand, is something they would’ve heard of in an exam setting.