We have a shared garden.
My children have a playhouse, sandpit, swing and various toys.
I bought them all and maintain the garden.
I insist my children share and would not let them make another child get out the house if they wanted it for themselves or similar.
My children are told not to bring anything out if they do not want to share as it is a communual space.
This wee boy will bring a toy out then abandon it - using our swing or trampoline.
My 2 year old will start to play with it and he gets upset and wants it back, not to play with just to stop mine having it.
He is 3, a full year older than my child.
His mother lets him snatch it back and mildly tells him it is wrong but does not insist that he shares.
This has happened more than once.
I won't because it is not his fault he is not taught to share.