Did a couple of test drive last week, didn't think of it much when they asked to make copies of my licence, obviously they copied both sides to make sure address is current.
Then I realised that the back of the licence has the Card ID number, that can be used to reset Service NSW password, and possibly other things like sign up to phone plans, apply for credit cards, and even retrieve credit report.
Should there be a need for concern?
Yes there is always a need for concern when sharing information.
Make sure the passwords you use everywhere are all different. Yes it's very difficult to keep track so write them all down.
I don't trust anyone at all but you want/need to drive the car and the only way of doing that is by handing over your licence. You have to take a risk somewhere. Keep an eye on everything that can be reset by using your licence number regularly but don't worry about it too much. You "should" be fine.