Software testers likely don't see testing as something to take pride in because they likely aren't sure if they've ever hit the mark. How are managers helping those who test understand what makes a good test plan?
My experience in the software development life cycle is that often, managers have no idea how the products work that their people work on. Most of the time, managers don't even know what kinds of technologies are involved in their product's stack or code libraries. Moreover, the things that make people tech minded people interested in their job I've found can often times be exactly opposite to what makes a manager type interested in their job. So by definition, it's often hard for the two to relate to one another on an interpersonal communication level. But most importantly. because of that large chasm of interest, managers usually have no way to help a QA tester know whether they are doing a good job. They likely aren't setting the bar for someone to shoot for. Human beings, by their very nature, like to measure themselves. Without knowing what makes "good quality tester" I can see why they aren't likely to take pride in their work.