Primarily it comes down to economics. Even the large drug companies have limits on resources, and they are going to submit to get a drug on the market in places where they can get the largest return on those drugs, and that's the United States. The United States prices for brand name drugs are two to three times higher than virtually any other country around. Second and third in terms of new drug prices are Switzerland and Germany. After the United States, you go to those two countries, because you can get more money back. Then they go to places like Canada, Australia and New Zealand, where the market size is smaller and prices are more controlled.
On June 11th, 2021. See this statement in context.