It’s not that your employees don’t believe in your company’s mission. They probably do, to a certain degree. They just have other missions that are more important to them—e.g., their families, their side-hustles, or their volunteer work.
So when they have the option of doing an extra hour of work, it’s a no-brainer when the alternative is wrapping up work early and going home to the missions that matter most to them.
Especially when that extra hour of work might not get noticed by their manager or might not have a substantial impact.