Unions made sense by the end of the 19th century, when we had no labor laws, and workers had no legal protection against potential abuses from employers.
Now unions became a political force used for money extortion and turf protection. For example, half of American workers earn less than $30,000 yearly. But workers making elsewhere $30k, if employed in a union shop would be making about double that. The point is that if we doubled salaries of all 50% low earning American workers, then it would bankrupt the country. Consequently, unions, which now represent only 6.5% of the workers in the private sector, use their political power to gain exclusivity here and there to extort much higher pay than the market otherwise would bear. Also, they use political cloud to ban non-union workers, by the way, the majority of Americans, from many jobs. For example, practically it is impossible to have any major construction job in Chicago done by non-union workers. It means the cost of housing in Chicago is much higher than it would be otherwise; hence, most Americans, not getting union wages cannot afford living in Chicago. This is an example how a political cloud that unions have, raises the cost of products and services provided by union shops, but paid by most of Americans who are not union.
In short, high union wages are not taken from the rich capitalists. They are taken from the 50% of the lowest earning Americans, as they are paid less but need to pay more for products and services provided by unionized shops.
If the author does not know these basic facts, he should learn them before writing about unions. If he wrote this misleading text despite knowing how unions operate now, he is or a paid union agent, or a crook.