There are different types of workers. Some bring their work home with them, while others clock out at 5pm and forget about work alltogether. Those who succeed typically feel responsible for their work regardless of whether they are in the office or not.
A portrait of a super-worker is the person who lugs a laptop with them wherever they go. If they go on vacation, the laptop comes with them so they can stay up to date with at least some of their tasks.
Getting workers to this level of responsibility is not easy, and in many cases not possible. But, if they are made to feel that their ultimate success or failure is tied to their reliability to getting things done, then they might start working when they are not expected to be working.
If workers feel that they will never get ahead no matter what, then perhaps they will not take any responsibility after they clock out. Instilling a sense of long range job security, recognition, and respect being tied to stellar performance is a job that a good manager needs to master.