About 35% of the world has its roads set up for driving on the left side and the balance is set up for the right. The origin of the difference is quite interesting and has nothing to do with one side being inherently better or safer.
In every country motor cycles, scooters and bicycles have their rear brake lever mounted on the side nearest the edge of the road. This is for reasons of standardization. It was argued that if you have two different bikes and got off one onto the other and the brake levers were connected around the other way it might be confusing. At least until you used the brake the second time. But it was really for the sake of standardization which is overall convenient.
When you think about it, it does not matter how the brake levers are set up. This is because our hands quickly learn where the bits of the handle bars and the respective controls are. When we move between bikes with different gear levers, be they bar-end, STI, rigger or twistgrip, we find that our hands quickly learn the setup. When we move between drop and more sit-up styles of handlebars we find the same. When we travel the world and ride on different sides of the roads, we quickly adapt. When people hire cars in countries that drive the opposite to what they had been used to, chaos does not descend upon them. They have no test to do in order to be allowed to drive there. It is assumed they will take due care.
This is why it is common for VWR customers in countries that drive on the right to not get around to having their brake levers connected around the other way. VWR bikes come supplied with the left brake lever connected to the rear brake and the right hand brake lever connected to the front brake. That can be swapped around at a bike shop but if it is not done it does not, in itself, seem to reduce safety.