In fairness, I think those "different reasons" are pretty significant (preventing people from fleeing oppression vs controlling the spread of a disease). You can criticize Australian COVID controls as heavy handed without comparing them so directly with a repressive dictatorship.

There is broad public support for COVID-related travel bans. In particular, the majority of people who are voluntarily staying home don't want the commons that is public health spoiled by a handful of selfish individuals who have decided that this is the personal liberties hill they want to die on.

The situation in Australia is particularly poignant because of just how effective the short, strict lockdowns have been— well, surprise, they're effective and therefore short because they're strict. When you take half-measures and pander to people who don't want to cooperate, that's when it drags on for months leaving those who cooperated feeling frustrated and exhausted (see: most of the US and Canada).