The decisions were made on the available information at the time, simple as that.
".....its about making poor decisions...."
Why is it a poor decision if you made arrangements to protect others on your return?
My sister knew there was a risk she may be stuck overseas, she accepted that risk.
She knew she would need to self isolate for 14 days at home, and she made the necessary arrangements for that to occur.
What wasn't on the table or a risk at the time, was being locked in a hotel room by yourself for 14 days.
If she knew the government was going to lock her up in a hotel room, then she could have assessed that before leaving.
The government should escort her to her home, instead of a hotel, so the government must wear the cost of their own decisions and pay the detention costs.