It makes sense if you think of a prompt not as a way of telling the LLM what to do (like you would with a human), but instead as a way of steering its "autocomplete" output towards a different part of the parameter space. For instance, the presence of the word "mysql" should steer it towards outputs related to MySQL (as seen on its training data); it shouldn't matter much whether it's "mysql" or "MYSQL" or "MySQL", since all these alternatives should cluster together and therefore have a similar effect.