It does not surprise me companies are making people go back to the office. Not just in Australia but around the world. There are a lot of people abusing the situation. It sucks but I saw this was going to happen when work from home first started getting rolled out back at the beginning of Covid.
The companies are going to use what ever means and reasoning they need to. But at the end of the day all that matters dollars. If they would have seen more productivity with people working from home and if the company made more money, the people would be allowed to continue to work from home
And there needs to be a WFH policy that states reasonable responsiveness. If on a break, set you chat status as such.
Of course there are workarounds, like just carrying you phone with chat app.
Then it really does boil down to people management.