The statement that physicists don't understand quantum mechanics is a bit misleading. While quantum mechanics is certainly a complex and often counterintuitive theory, physicists have a deep understanding of its mathematical formalism and its predictions. They have been able to successfully apply quantum mechanics to explain and predict a wide range of phenomena with remarkable accuracy.
However, the interpretation of quantum mechanics, which concerns the meaning and nature of the theory, is still an active area of debate among physicists. There are various interpretations, such as the Copenhagen interpretation, the many-worlds interpretation, and the pilot-wave theory, among others. These interpretations propose different ways of understanding the underlying reality described by quantum mechanics.
It is true that quantum mechanics challenges our classical intuitions, and some aspects of the theory can be difficult to grasp. Physicists continue to explore and investigate the foundations of quantum mechanics to gain a deeper understanding. While it is not entirely accurate to say that physicists don't understand quantum mechanics, it is fair to say that there are open questions and ongoing discussions regarding its interpretation.
Regarding Sean Carroll's perspective, it's important to note that interpretations of quantum mechanics are subjective and vary among physicists. While Carroll may argue that physicists do not "want" to understand quantum mechanics, it is more accurate to say that there are different philosophical viewpoints and preferences regarding the interpretation of the theory. Some physicists may prioritize mathematical formalism and empirical predictions, while others may be more interested in philosophical implications and understanding the nature of reality at a fundamental level. Overall, the pursuit of understanding quantum mechanics remains a central focus for many physicists.