There is no law against backing out of your driveway
If there were, how would you ever get your car out of your driveway again?! (Sometimes it is not safe to reverse into your driveway and not possible to turn around once in it; therefore you would have to go forwards into it and would be forced to reverse out of it).
The law says this about reversing:
“Caution in backing vehicle
193 The driver of a vehicle must not cause the vehicle to move backwards into an intersection or over a crosswalk, and must not in any event or at any place cause a vehicle to move backwards unless the movement can be made in safety.” (Motor Vehicle Act)
When most people reverse out of their driveway they are simply reversing onto a street mid-block, which is not considered an intersection (an intersection is a place where one road meets with another road; where the road meets with a parking lot, lane, or driveway is not an intersection). So unless your house is located in the middle of an intersection or ridiculously close to one (anything is possible I guess!) then I can’t see how it would be necessarily illegal to reverse out of your driveway. Also, when you reverse out of a driveway you may be reversing over a sidewalk, but probably not a crosswalk; the crosswalk is the thing located AT the intersection.
So, make sure it is safe and clear, then reverse. (Yes please signal for this. Others may be able to see your signal, including people that you are not aware of – legally you must only signal if there’s someone to signal to).
If you can, reverse INTO your driveway so that you don’t have to reverse OUT of it; usually that is a much safer option with much greater visibility. (When you reverse in, you can check out the space you’ll be reversing into and then reverse; when you reverse out, the space you’re reversing into may be constantly changing).
In instances where you must reverse with poor visibility, get a spotter, or at least sound your horn to alert others.
Keep in mind, vehicles exiting driveways (whether it may be forwards or backwards) are required to yield to road users already traveling down the road.
Keep in mind basic right of way, though. If a vehicle has already reversed from a driveway onto the roadway and then a vehicle travelling down the road is approaching, the approaching vehicle is now legally required to yield, since the vehicle exiting the driveway was in the space first. If you see someone trying to reverse out of their driveway and you want to stop and let them out, that is fine – just make sure it is actually safe to stop considering the vehicle(s) behind you, road conditions, etc.
Just be careful and use your common sense. Be kind to one another!