Ask HN: Employee retention software

Employee retention seems to be as large a problem as employee hiring. However, there are so many tools and softwares dedicated to application tracking and onboarding. However, very few to employee retention. Why is that?

Is it because it is a hard problem to solve through software and much more cultural/programatic or is it because it is not a problem really. And employers don't give a crap about 95% of employees and can focus on retaining the 5% without any tool.