In the United States, much of what unions sought at their founding, have become a matter of law, minimizing their importance and need.
Big labor, the auto workers, steel, and rubber workers, sought benefits and work rules that coupled with uninspired management, destroyed these once back bone industries in America. Their biggest problem, in order to justify their existence in the '70's and '80's, continued to seek more and more in terms of remuneration and benefits, and, in the industries cited, management, in order to "buy peace," kept on giving, but since the '90's, these industries have disappeared substantially because their labor costs made these firms non-competitive. The significant reduction of those industries today is directly attributable to their "accomplishments" in these decades noted. There are today, however, responsible unions, even in the steel industry.
Despite my criticisms of the big labor unions I referred to in the paragraph above, there remain, unfortunately, irresponsible corporate management that keeps the need for unions to exist.
Public employee unions are not necessary, and help keep government inefficient and too costly.