You could say that the managers don't understand what it's like on the front lines or in the trenches.
Both of these expressions come from warfare, the second specifically from WWI trench warfare. When combined with some sort of statement that someone doesn't understand conditions they would give the suggestion of commanders who are asking soldiers to do things without fully comprehending what that means for the soldiers. Or in this case, of managers who make decisions without fully comprehending what difficulties they will cause for employees actually asked to implement those decisions.
on the front line of something also on the front lines of something,
leading others in an effort to change something For years the group
has been on the front line of efforts to educate people about global
warming. Doctor Tay is on the front lines of improving treatment for
people with head and spinal injuries.
Etymology: based on the military use of soldiers on the front line
or front lines (closest to the enemy and very important but also
those most likely to be hurt or killed)
("on the front line of." Cambridge Dictionary of American Idioms. 2006. Cambridge University Press 29 Sep. 2016.)
in the trenches
working in the most active and difficult parts of a job or business:
The boss understands the difficulties we face here in the trenches. He's a salesman with 30 years of in-the-trenches experience.
("trenches." Cambridge Business Dictionary. N.D. Cambridge University Press 29 Sep. 2016.)