Even if NSW does not directly pursue the debt, these things have a way of catching up with you and doing so at the least convenient times. Interconnected databases, miscoded references and the like can wind you up not only with entry problems in Oz, but elsewhere as well. That "elsewhere" may misread a code for "unpaid moving traffic violation" to mean something much worse than it is.

Some day you may actually need to go back to Oz, your flight may be diverted, you may have a business need or somesuch. Maybe you will still live in Europe but want to work for a company HQ's in Oz which does a routine check. By then, the $278 will be 50x that and you will be stuck quietly paying it.

There are enough horror stories about people denied entry or arrested and held for days on incorrect information to make any sane person not want their records cluttered with things which can be easily misinterpreted.

Either contest if you still can or pay up.

If it seems as though it's too much money for what you did, that's a legal argument to make and has nothing to do with skipping out.