It's worth noting that this kind of data isn't published by the FAA - rather, ADS-B transponders openly transmit information and anyone who wants to is (at leas

It's worth noting that this kind of data isn't published by the FAA - rather, ADS-B transponders openly transmit information and anyone who wants to is (at least technically) free to receive it. This includes commercial and hobbyist networks of receivers that report information to web services like this. The FAA in the US does publish a 'privacy list' of aircraft whose owners have requested that they not be included in services like this, and most commercial providers comply with that list, but enforcement is sparse and several hobbyist projects (e.g. ADS-B Exchange) do not and even emphasize aircraft that have put in such a request, since the tend to be a bit more interesting. A bit of a Streisand effect. The same situation exists with the similar AIS system used by ships at sea, and has produced concerns over malicious use, but there continue to be plenty of websites that will show you maps of ship locations picked up by their contributing AIS receivers.