First and foremost it's a public service, the taxpayer comes first and profit later, if indeed it does need to make a profit.
If i'm not mistaken the early morning owl service was initially set up as part of the anti drink-driving campaign (2018, Spew'n Juan and all that?), so it's clear the service was set up for a public service reason. It wasn't something that was just plucked out of the air. Whether 01:15 or 00:15 should be the last departure time I guess should be up for evaluation. However, using state assets for private hire after either of those times and without that review/evaluation taking place is simply wrong.