It's one of the core superpowers of the Australian electoral system: you can be fined for not voting, but also just about _any_ excuse will get you out of the fine - the fee itself is considered to be administrative and waived once you provide a valid reason.
But the system itself means that voter suppression is vastly more difficult: people are inclined to turn up. Or at least participate with the system. And the elections themselves then have a check system built in - if a whole district is getting fined, well now that's news - people complaining to media, sending letters etc.