"Tactical voting" means you vote for a less preferred candidate over your preferred candidate to achieve a desired outcome. This is not the same a giving a sec

"Tactical voting" means you vote for a less preferred candidate over your preferred candidate to achieve a desired outcome. This is not the same a giving a second preference to an independent. In your example, the voter has voted for their preferred (Labor) candidate over the independent. If the Labor candidate gets knocked out then their second preference says "if I can't have Labor then I would prefer an Independent over Liberal". That's the beauty of preferential voting, you generally don't have to vote tactically. You just vote for what you really want.