To be honest, kangaroos are very docile and easy to scare away. Taking food out of any animal's mouth will get a response, even my little mild dog.
We used to camp at an unserviced camping ground on the south coast where the kangaroos were up close, the kids could feed Rainbow Lorikeets (Parrrots) out of their hands, and we couyld sing and play guitar around fire until early morning.
One night we left the leftover curry in three legged pot next to fire, and about an hour after going to bed, still p*ssed, we heard a commotion outside. Unzipped the tent, and shone torch, and two kangaroos had toppled the pot, and staring at us with curry all over the snout. Wew just cracked up at the funny sight. We tried to shoo them away, but the curry was too nice I suppose, and we left them to it.