Who says how long the data is being kept and where it’s going?
The government says. They're the ones operating the cameras. Absolutely, they should not be used for any other purpose than their stated one. No video saved, only still frames kept long enough for the AI to make a determination, and kept longer if that determination is that there was a phone detected, so the photo can be used as evidence.
But in that situation, where the government is operating it in accordance with security and privacy best practice, the safety benefits far outweigh any theoretical downsides. This is not some theoretical. Over 1000 people die every year in Australia on our roads. Approximately 16% of serious car crashes are linked to mobile phone use.
We need to stop treating driving like a sacred right, and start treating it like what it is: an incredibly dangerous activity in need of heavy regulation.