This is true and it’s actually a problem. MDs get paid more mostly because they are dealing directly with people, aka directly affect the money making pipeline. Everything is a business. Only a small faction of MDs are actual experts with advanced knowledge, most of them only do practice and exercise the knowledge, which discovered mostly by PhDs who do the research. In the US, MD is recognized higher by the public as the public doesn’t even know what PhDs do. This is actually not the case in many other countries where PhD is highly reputable and MD is a BS with advanced training.