Garuda are banned in Europe. Why the hell are they not banned here.
A fair question but the answers are not necessarily logical.
Apart from the political decision of placing a ban on the airlines of a near and powerful neighbour, there's the consideration of some form of reciprocity. A ban on the use of Indonesian airports probably wouldn't cause much of a ripple (except for the loss of adequate airports for ETOPs operations), but the major impact on Australian aircraft woulkd be the loss of overflight rights - flights cannot avoid Indonesian airspace on routes to Asia and Europe without major impact. Think about it!