It's very simple ("Beware of simple solutions to complex problems" :-) ): The organization and/or the developers responsible for the day-to-day development and

It's very simple ("Beware of simple solutions to complex problems" :-) ): The organization and/or the developers responsible for the day-to-day development and maintenance of the application do not care enough to go back and refactor code once it has become apparent that there is excessive duplication of code and that the duplication/intimacy with the code has revealed the patterns that are necessary for the refactoring to be successful. I'm not sure if there's any sure-fire solution to this issue, other than (possibly) increased pay/benefits or some other form of reward. After all, developers that care in the first place don't normally require extra rewards for caring because they view the end result as the reward (clean code that is reliable, performant, and satisfies the end user/customer). So, at most, you might gain some extra, superficial "caring", but how long-lasting that will be is anyone's guess.