You want learning to be regulated. Standardized. Average. Leveled. Predictable. And frankly not that exciting.
So to have a movement where learning is unregulated, un-measured, unaccounted for is frightening. Nobody knows what they know except the learner- him or herself. Tests can't tell us because tests are not applicable in unschooling.
And from there you can categorize him or her.
Do you see what is wrong with this picture? Someone creates the agenda. Someone has the power to decide what you should know and what should be omitted. Ask yourself, why is this be allowed to happen?