I'm in management, have been for about 5 years. I've never found it difficult to judge the productivity of my team members. Even in the 15 years I was primarily an IC it was obvious, to me, who the most productive people on the team were and who were the least. If you are actually involved in the work the team is doing, and if you take even a little bit of time to have an actual relationship with people, it is not hard. What to do about it (besides the lazy "fire them") can be very hard. Helping people grow can be very hard, depending on the people. But my team doesn't work "for me," they work with me. I'm as much responsible to them as I am for them.

As another comment points out, the people that use these tools would never give their reports the same data about their own "productivity." Employers try not to even let employees know about this kind of surveillance because it directly undermines any supposed "team culture." They have no place in an equitable relationship. When management uses these kinds of tools they make it clear that they don't care about those being managed. They don't care enough to be honest with them, to be accountable themselves for how they manage. The obvious message these tools send to those under this kind of management is that that management does not see them as respected colleagues and team members, but rather cogs in the machine, "resources" to be exploited.