Yes, even on private property, including the driveway of a free-standing house. However, the law actually says that you may not “detain” a vehicle once its owner has asked for it to be released. The queue of volunteers prepared to respond to these requests from angry drivers might be quite short. The fairly dubious argument about a wheel clamp potentially damaging a car also applies in a roundabout way to a bollard, if the driver damages the car while trying to manoeuvre out of the space. Have a look at this fact sheet.
The most elegant solution that I have found was the building where committee members would volunteer to park their cars with a wheel clamp attached under a sign near the car park entrance that said “We clamp illegally parked cars.”
Also have a look at sections 650A and 651C of the Local Government Act 1993 No 30 – NSW Legislation.
Getting back to the original question – about residents parking in visitor parking – the strata scheme needs to issue Notices to Comply to rogue parkers and if there’s any issues with the definition of that – I would say a resident is by definition not a visitor – pass a by-law defining what a visitor is for the purposes of their scheme. Once an NTC has been issued, you can apply for fines for any further breaches.