Average programmers tend to: * like new projects * want to build "new things" * not like fixing bugs * not like reading code * not like to redo their designs/code * think their code is as good as it gets
Good programmers on the other hand * tries to find joy in thr task at hand * thinks their old code is bad * aren't invested in their own designs * don't fear trying solutions * reads code rather than docs about the code * don't mind fixing bugs * happy when the code quality goes up, hates it when it goes down.
In other words - good coders CARE, average coders just want to have fun and build stuff. This means the latter group doesn't build the understanding of how to build good, bug free code. They prefer to build themselves into a corner rather than throwing out their designs. Thus they get less practice.