[slg]

>If public has access then normal laws governing motor vehicles are applicable

Laws certainly apply, but not necessarily "normal laws governing motor vehicles". For example, you probably can't be ticketed for running a stop sign in a parking lot on private property. However, you would almost certainly be liable for damage if running that stop sign caused an accident and you could be potentially charged with some type of generic reckless driving offense. Obviously the laws vary by jurisdiction.

[bigiain]

As you say, it depends on the jurisdiction.

Here (Australia) the rules define "road related areas" as including private property that does not have a "normally locked gate" protecting access.

This means all road rules (including stop signs, alcohol/drug rules, mobile phone use, and speed limits) apply in places like publicly accessible carparks on private property, and homeowner's driveways if they do not have a "normally locked gate". People have been booked for drink driving and mobile phone use sitting in their cars in their own driveways here (almost certainly after "failing the attitude test" and pissing a cop off enough for them to punitively enforce a stupid interpretation of a poorly written law, but that's a different rant...)

[dragonwriter]

In CA, local governments can and often do pass ordinances allowing Vehicle Code enforcement on certain. Private property; this is most common on parking lots and private roads that are generally open to the public.

And law enforcement investigates and assigns fault in reports for accidents on private property even where vehicle code (other than hit and run and DUI, which IIRC apply everywhere) does not apply.