Yes that's true. Most of the Left Hand drive world is former British colonial. Except for the population size of India, the vast majority of the world drives on the Right. If a company wants to produce vehicles, do you incur the expense of an entirely separate build process for a small minority of the population? Some might but most would pick the majority and build for that.
Japan is where we get a lot of our cars from... And they're RHD. So even if companies like tesla stop producing them we'll still have others to buy from