This very same argument could be made against liberal democracies, where there is a potential for similar dynamics of corruption to develop. However, almost no

This very same argument could be made against liberal democracies, where there is a potential for similar dynamics of corruption to develop. However, almost no one would argue that liberal democracy isn't preferable to a system where one person or a small group can decide everything. Unions give you a vote and that is better than the alternative. Preventing a union from becoming corrupted is another problem and there is a wide spectrum of structures among unions, not all are as you depict.