It's not intrinsically better, it's just a convention, but it helps if everyone operates to the same standard for obvious reasons. Since neighbouring countries drove on the right, it was better to adopt the same standard. This was not an issue for islands such as the UK and Japan with no direct road links to neighbours, therefore they still drive on the left. Originally, before cars, the nobility rode their horses on the left to defend against oncoming traffic since they held their swords in their right hand. For that reason, peasants travelled on the right for safety. After the French Revolution it was prudent for the nobility to blend in, hence all traffic began to travel on the right which was then spread by the French empire.

I assume you mean worse. Driving on the left was worse because the steering wheel was also on the left, reducing visibility. For some reason Swedish car manufacturers in the 60s, which was a big industry, didn't produce cars with the steering wheel on the right.

Side doesn't matter in itself, but all our neighbours drove on the right side, which in itself is a good enough reason to switch.

I believe the parent post is saying that right-hand is better, but I'm curious on the question in either direction.

There were (are) roads that wound across the Norwegian border and back again ....