BUT bear in mind that typically these birds are being regularly flown and exercised for falconry displays - they're certainly more likely to be able to engage in free flight or thermal riding than any aviary birds.
This is a way practically 100% birds used for falconry are beeing kept in the Czech rep. now. Only activelly breeding birds are kept in aviaries. Or those where there is no plan to use them for hunting/display flys in that given season.
Most of general public don´t show negative reaction to tethered birds, they are rather curious and ask questions. So that it continues as a tradition and standard. My own opinion is neutral, but it is maybe because I have some friends between falconers and sometimes take part in their hunts so I´m used to it.