You seem to be referring to the South Australia Home Quarantine app [1]. There has been a lot of misinformation circulating about this app recently. I'd just like to clear up some things:
The app only applies to people that need to quarantine, not the general population.
The app allows people who are required to isolate to opt to do their isolation at home, rather than stay at a quarantine facility. Nobody is being forced to use the app.
It is a way for authorities to make sure people are quarantining correctly, and to follow up cases of contact if people break their isolation bubble. Police are not arresting people for failing to check in. (My guess is that they would reset your isolation duration, follow up contacts and/or move you into a managed quarantine).
The app only applies to people that need to quarantine, not the general population.
The app allows people who are required to isolate to opt to do their isolation at home, rather than stay at a quarantine facility. Nobody is being forced to use the app.
It is a way for authorities to make sure people are quarantining correctly, and to follow up cases of contact if people break their isolation bubble. Police are not arresting people for failing to check in. (My guess is that they would reset your isolation duration, follow up contacts and/or move you into a managed quarantine).
[1] https://www.covid-19.sa.gov.au/home-quarantine-app