Thanks mocoman for a rational posting and I am sorry if my initial response seemed off-hand.
There are a number of reasons why I often remind people of the law regarding scanners. Firstly I was a professional user of the radio spectrum for most of my life and am still a "hobby" user so I view radio as an essential and precious commodity which should not be abused - lives depend on it. I don't make the rules but see it as very sensible practice to remind people of the error of their ways if they bust those rules. If Sarah123, or anyone, chooses to purchase radio gear and listens to the air, police or whatever bands that is up to them but they should be aware of the law. Unfortunately, when one purchases this type of equipment the dealer will be more interested in earning his money than warning potential buyers what they can and cannot do. In an ideal world equipment for "restricted" bands should not be available to the public unless the purchaser can prove a legitimate interest.
Whatever any of you think, it is ILLEGAL to listen in to transmissions for which you are not authorised and this subject has been done to death on here a thousand times. It is also ILLEGAL to discuss in public anything you may have heard.
Policing of the radio spectrum in this country is virtually non-existent, which is why irresponsible people can buy air band transceivers and play at being air traffic controllers and pilots. Presumably none of you have experienced the results of such madness? I have and it is incredibly dangerous and terrrifying. I was directing commercial jets into Heathrow one day when someone decided thay could do it better and passed instructions to an aircraft. This resulted in a dangerous loss of separation. There are other controllers and pilots who can tell similar stories.
Don't ask me why the police ignore users of air band radios.... or why airport shops sell them.... I cannot answer that. All I can do is to remind people of the law and implore them to be sensible if they own such equipment.