except that:You don't seem to understand this basic concept, so let me try to explain it in a simpler way.
1. Union negotiates a deal so that every school has a security guard.
2. Every school has a security guard because of the union.
3. The union was able to negotiate that deal because of teachers who paid union dues.
4. Teachers who did not pay union dues benefit from the action of an organization they did not contribute to - they are free riders.
5. Half of the schools in the district do not need security guards, and yet the teachers who work in those schools have their compensation reduced to pay for the guard that they do not need.
People are individuals, and circumstances vary. That is why socialization of compensation is typically not that great a bargain for many who are then told that they have to pay up "because they are benefiting." You are confusing your beliefs with facts. A Closed Shop is basically the union telling the workers that they must each subordinate their preferences, needs, and desires to that of the collective, as expressed by the Union.