for the same precise reason that "copying is not theft"

any single one of the measures you've cited removes the ability of the
socially-agreed upon owner of an object, or holder of a job, to use
what they "own" as they see fit (the teacher angle is a bit of a wierd
case in your argument, but it doesn't break entirely).

however, in the case of a creative work, the work's life begins at
some point (or period) in time when its creator decides that s/he
wants others to see/hear/touch/smell it. it doesn't take anything away
from anyone to say *at that point* in time "the creator decides who
can make a copy of this".

making cars illegal to help bus drivers hurts car owners. making
washing machines illegal to help washing ladies hurts owners of
washing machines. placing limits on the ability to copy someone else's
work hurts no-one if those limits are sensible.