Arguments against unions sometimes stem from the employer’s perceived inability to offer higher wages for products at a low enough price that they can successfully compete with rival companies.
Some argue that unions devalue a worker’s merit. The idea is that, at a union company, no matter how skilled a worker is, he may only progress at the same rate as all union members progress; in other words, rate of progression is scripted by the union. You may deserve a raise or promotion, but you won’t get one until “it’s time.”
Merit also ceases to matter when unions guarantee members their jobs. It’s one thing to demand that workers not be fired for forming a union, for demanding that employers obey labor laws, or for negotiating for better pay and benefits. It is another, however, to prevent employers for firing employees who are simply not very good at their jobs.