Tickets should be transferable with many more services during peak hours. Incredibly, Mt Eden station doesn't have a timetable. The only way you know you haven't missed the train is by getting there very early and hoping there are other people around - preferably not the derelicts who sleep in the platform shelter. I drive now, if I made a change I'd get the train, leaving home at 7.40am compared with 8.05 by car. I wouldn't need too much encouragement to switch to the train.
Cost is one factor, that journey home time another.
I have used public transport but the lack of buses at peak hours has put me off. It is much more pleasant not driving in peak hours with stressed people off to work, but having to leave an hour and quarter earlier to fit in with bus timetables makes sitting in traffic bearable. That's approximately 90 minutes in the morning, an hour at night - a journey that takes me 15 minutes by car. I now leave 6.30ish - to catch a direct bus to the city with a stop in New Lynn. That can take an hour to an hour and a half.