I'll answer this question with some of my general knowledge. Let me know if I helped you or not.
I believe officials were opposed to labor unions when they began to acknowledge how much of a threat it would be to manufacturing and other sorts of jobs. Labor Unions are similar to going on strike, or protesting something. With protesting laborers, businesses and factories would drop in revenue and would become unproductive. They would end up having to increase pay and improve working conditions to earn their workers back. This is equivalent to the loss of income for businesses.
I believe times changed in the 1930 because the American economy was extremely poor. The 1930's was the time of The Great Depression, multiple stock market crashes, and The Dust Bowl. These events hit hard and poverty became <em>wide spread. </em>
