The situation of teachers before the modern teachers union movement looked pretty bleak: they earned incomes less than car washers, they were forced to eat lunch while supervising students, and they had to bring a doctor's note if they called in sick. It sounds like they were treated like children themselves.
Kahlenberg warns that abolishing unions would not put the interests of the students at the top. Instead, it would increase the power of "other adults in the system": superintendents, principals, and parents (who predictably put the interests of their own children above all children). To that group I would add School Board Members and private special interest groups and individuals in the corporate world who fund their campaigns.
And conservative privatizers (supporting school vouchers) would like nothing more than to see the destruction of teachers unions, because those unions are the only ones with the political muscle and strategic capacity to fight privatization of public education. Quoting the founder of teacher unions, Kahlenberg warns:
conservatives want to kill [unions] because essentially we form the strongest liberal base in the country ... But the liberals don't realize who their friends are.At least on Labor Day, let us liberals remember what friends we have in the teachers unions, even though they are not perfect and do have some weaknesses to work on.