ur2 and SydGirl and KaptainM are correct but here's the rub. If you miss your bus or train there will be another one in 10/15/30 minutes time and the ticket you purchased will allow you carriage on that bus or train.
That is because the bus and train are classed as "common carriers" and you'll find that airlines (in Aust at least) are specifically exempted from being "common carriers".
A question for the more knowledgeable:
You want to fly from Hobart to Proserpine so you ring J* and they make the following bookings for you:
Hobart to Brisbane J*82 departing 0600 arriving 0840
Brisbane to Proserpine J*756 departing 0955 arriving 1130
You arrive a Hobart airport at 0505 happy that you will check your bag, get your boarding pass and still have time for a coffee.
Then comes the announcement "J* is pleased to announce that their Boeing 717-200 flight 82 for Brisbane is delayed due to <insert common reason fed to the masses here>, we have techs working on the problem and hope to have it solved soon".
Where do you stand with missing your connection to Proserpine because of J* being late out of Hobart or even cancelling that flight.
Just a thunk.