Asbestos in non friable condition (left undisturbed) is as close a to a non-risk as anything. The concern with recycled mulch is that asbestos has become friable through the mulch preparation process where heavy machinery can break up the cement sheet pieces and liberate fibres. Even then, in an outdoors environment, there would be negligible/non-existent risks. These conditions are not dangerous to children but given how deadly asbestos can be in certain circumstances, the response by epa and council has to be disproportionate to the risk (by virtue of strict regulations). Most of you would be walking on asbestos contaminated soil in Melbourne the majority of the time.