And again, the potential for harm is greater than the potential for a good outcome, because the threat of fines will make people avoid getting tested and hurt contact tracing efforts. Testing and contact tracing is more important than the possibility that a few people might be deterred from risky behavior by fines. People won't go down to get their nose swabbed if they think there's a chance they'll get fined for being stupid. They won't tell you the truth about how they got sick if telling the truth means they face a punishment.
That makes no sense, there is nothing illegal about getting sick or needing to be tested. If you know you have been exposed and carry on normally without being tested, you are a menace to your fellow citizens.