This is simply not true. There is reason for collective bargaining, even from the perspective of the employer; else companies like ManPower and ADP would not exist. The factory owner would rather not deal with personnel details.
Unions in their current form would not exist without government force applied against property owners. That does not imply that there would not be any form of collective bargaining. Trade guilds could engage in collective bargaining to the benefit of both workers and employers, if such guilds were in a position where their continued existence relied upon their ability to do so. If a trade guild refuses to accept or retain members who are not good workers, employers who hire workers from the guild would likely pay extra for doing so, but might find it easier to get quality workers than if they search for workers outside the guild. Of course, the more tolerant the guild is of bad workers, the less advantage employers would see to hiring them, and the less money the guild would be able to demand for its workforce.
One thing that I wish more people would realize is that the real battle isn't between workers and employers, whose interest substantially overlap. The real battle is between union workers and non-union (actual or prospective) workers.
Disagree there. I think the unions have done a fabulous job of serving the interests of the international banking interests that spawned them. They have forced exportation of our nation's manufacturing infrastructure (essentially a form of intellectual property) for fun and profit. Our enemies now possess the latest information to make everything from screw machines to plastic resin synthesis. Unions have facilitated taking America into socialist dictatorship from the top down. In that respect they are almost as damaging as environmental and safety regulations.
Hence, the real battle is between collectivism and private enterprise.