Kristofg,
In the US, the multiple laws regarding the legal carrying of a weapon/gun by a citizen vary by state to state.
And some of those variations include different places where even a legal CCW (concealed carry weapon) may not be carried legally. Some states may have the law allow a business to bar/ban a legal CCW from being carried into that business. Or the state law may not allow the CCW to be carried into certain types of places in general.
There are variations, and conditions, and requirements, and exemptions, and prohibitions, and all sorts of hoopla and rigamarole regarding legal CCW in the US.
Now as to the original topic, boy that stinks. Regarding officers losing their pistols in various places, it's the real world and some folks get careless or distracted. Personally, I think they are idiots to not realize they lost their pistol in the bathroom/wherever.
And embarassed to claim their pistol? Then they really are idiots. If the lost pistol is found by good guys, then they report it to the police, who would trace the serial number and find out just who owns the pistol. If the lost pistol is found by not-so-good guys, it gets used in a crime or crimes.
IIRC, there are all sorts of 'LEO lost pistol' stories about. Let's see, I remember the tale of the woman LEO who left her pistol in the bathroom in the 'secure' area of an airport. etc. etc, etc