Yep, uh... We're going to need a demonstration. Not exactly getting what you mean.
Okay. I live about an hour train ride from the city. So I'll go to my bus stop and buy a daily zone 1 and 2 ticket.
So I'll bus to the station which is still zone 2. Then I'll hop onto the train, because my metcard is for all day, and I can ride all public transport. So I'll then ride the train, and then get off at Flinders Street, and i'll be in the city which is zone 1 (Although zone 1 starts at Camberwell for me)
So then after the train ride, say I need to get lunch and then a tram ride to a friend's house. So I'll go and get lunch and then take a tram ride to a friend's house.
What I'm saying is instead of just being limited to only being able to take a train ride to somewhere and back, where you can't get off if you need to do something short noticed (Like you need to pee badly or something) with a metcard it covers the whole day, instead of a "return" or "one way" ticket.
As I said before, I'm comparing it to Sydney because I don't know much about public transport in Brisbane.