The general, mundane public is not.

Most of the Secret Service and Big-Wig officials have a vague idea of what is going on, but don't know enough to actually lock down the Summoners. They're only really a match against the weaker Summoners, who don't know enough to be of any use. 
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Edit; A lot of things I could have added to the OP have been excluded for the sake of brevity and flexibility. Again, I can't stress enough how willing I am to answer questions or even accept entirely original material.