Yes, the collective bargaining of trade unions hurt the economy, because companies cannot afford to keep up with what the trade unions want to be paid. The trade unions want people to be paid far more than what the market can afford. The unions do not care about the company, and a lot of businesses, like the car companies, go out of business.
Collective bargaining, per se, doesn't hurt the economy. What does hurt financially about collective bargaining is the "ends justify the means" philosophy employed by the unions to achieve this goal. Union behavior, of late, appears to be very thuggish, not to promote an improved work environment for union members, but to fill union coffers in order to produce an outcome favorable to unions in elections. Sad, but true. Collective bargaining gives, not workers, but unions, advantageous outcomes.
I personally think that the trade unions are crucial to achieving equal societies due to their involvement in social justice. During the last few decades, however, this function has been questioned because of the increase in inequality in rich and developed societies where trade unions still retain part of their influence
Only to right to work states does it hurt the economy. They do not like unions and they seem to be anti labor. They do not to like when their employees have a voice. In unions, every employee has a voice and they get to decide what is a fair wage. How is that so bad? It is only bad if you don't believe in treating your employees with respect.
I believe the economy functions better when more people have more money or buy power. I believe the collective bargaining of trade unions does more to help the economy than harm it. With collective bargaining employees are far more likely to receive benefits and a living wage. With these benefits employees can easily grow the economy with their pay checks.