FRA is only bad for departures (or for transit, as the AC is outside of security so you either cannot access it while in transit or have to go through the security hoopla though it is much easier for non-US departures. All airports everywhere in the world that are not sterile are forced to have a secondary search at the gate for US bound flights, this is not unique to BRU. Some airports have reconstructed the gate areas to become sterile and avoid this check.