Monument symbol without monument

This reminds me of an incident several years back...

We were constructing a roundabout where there were two mon's IIRC; a licensed surveyor in our agency declared them as SFNF. I got a call from the private surveyor for the contractor, urging me to search for and tie the existing monuments before they were lost to history as he believed they were paved over a while prior to our construction. Sure enough, there they were- under about 0.10 foot of asphalt.

Not good.

I wonder how many times the "SFNF" abbr. has been applied as a result of a simple lack of due diligence...? I'm not saying I'm perfect myself, but simple "drive-by searches" are simply verboten in this profession.