slamming the open-door in people walking outside the door is another.

That might be true in a small shop, but in a lot of places the bathrooms are recessed into a hallway where nobody who isn't trying to get into or leave the bathroom should be standing.

You can defend against someone forcing their way in, by using your body weight against door, something you can not do if it swings outward.

Is that really a concern...? The amount of conditions that have to be true for this to become a thing seems really long... boarding on the "your insurance policy covers you if an elephant falls through the roof on the first day of February" cartoon levels of specificity.

Not to mention if you assume a truck stop instead of a restaurant. It might be harder to use your body weight to keep a door closed, but with a proper door frame, deadbolt, and security hinges, it would be basically impossible for some hypothetical attacker to break down the door.

Odor control is another issue, door swing outward will release the smell into next room, rather than contain it with the swing inward.

Um, no it won't? This is actually backwards the pivot of a door that swings back into a room, will force air out of a room with it swings out. If it swings out, when it closes it's going to push air back towards the room.

In either case, I'd expect basically no observable impact on the amount of perceivable smell.

accessibility demand the door swing inward for people in a wheelchair so they can operate it.

They still have to get out...? It's not our handicapped folks are getting stuck in bathrooms are they? And if they are, wouldn't that be a reason to change this?

this is a building code bylaw,

I'm struggling with the rational