It's not a question of cultural positions but more a question about why airport communications were added to an exclusion list when it's perfectly legal listen into all other private signals bar police radio (as far as I'm aware). Even collecting data on private WiFi broadcasts is fair game; as we learned when it was exposed that Google Street Car was doing just this.
It's pretty obvious why it was made illegal to eavesdrop police radio but less clear why airport communications are also illegal. So I find it odd (baring in mind I'm speaking from a position of ignorance - which is why I'm raising this question) that airport communications were added to what seems a pretty sparse list of excluded broadcasts.
Maybe it's just another example of laws not keeping up with technology? ie that law originates from a time when radio transmissions were pretty limited to private and public broadcasts whereas nowadays most of our private communications are also broadcasted via some frequency and waveform - albeit we now have automated encryption/decryption techniques to protect our correspondence. So if the law was written now it would be more like a whitelist of content you could listen into (eg radio and TV broadcasts) rather than a blacklist of specifics you could not. I'm just guessing here though.