>You should always look both ways regardless of which side a car is driving on.

This is true, but when I finally went to a right-side country (Czechia) at age 29, I discovered that contrary to what I believed, I must not be, because I kept only looking right.

Concur. I believe that regardless of whether you look both ways or just one, if you're not expecting cars to be oncoming in a certain direction you're unlikely to see them.

When crossing two-way streets in countries that are opposite my own, I found it's trickier than it sounds due to some subtle subconscious thing even when you look both ways.

I think they're referring to places like roundabouts where you can cross halfway and the traffic only comes from one direction. Cars would never reverse off a roundabout and it's illegal and pretty dangerous to bike into a roundabout from the wrong direction.

The last percentage of risk is whether you bother checking for things that "can't" happen because "nobody would ever do that."

In primary school, we learned to look 'left, then right, then left again' before crossing. This is really muscle memory for me now.

That would have to be reversed in a country with left-side driving.

You are correct to worry about cars in reverse. I was nearly killed crossing the road when some idiot decided that going at 50km/hr in reverse up a one way street was a wise idea.

The order matters too and is different if people drive on the left or on the right