We’ve had these possible false alarms for a while.
False alarms can paralyze as well.
Yes, though the publicity of the hoaxes possibly inspires copycats. I remember silliness started after 1995 OKC bombing - blocks closed off here (Pittsburgh PA) for small, unattended boxes or briefcases, powdered sugar, pepper spray clouds etc. Just idiocy. I don’t know what the answer is though.