One hypothesis that may explain the bad perception of unions is if there has been continuing investment and efforts in anti-union propaganda by pro-business or pro-corporate groups.
A similar argument is put forward by Kerryn Higgs' book "Collision Course: Endless Growth on a Finite Planet", to explain why society takes direction from economists, in pursuit of economic growth, rather than taking direction from science. Higgs' book is focused on trying to explain why society is failing to tackle climate change, not an analysis of unions, but some of the history that is presented regarding pro-business propaganda is eye opening. Here is an excerpt of an interview with the author:
> How did scientists lose credibility? When I was young, science was almost a god. A few decades later, scientists were being flippantly brushed aside. How did economists displace scientists as the crucial policy advisors and the architects of public debate, setting the criteria for policy decisions? How did economic growth become accepted as the only solution to virtually all social problems—unemployment, debt and even the environmental damage growth was causing?
> The new corporations of the early 20th century banded together into industry associations and business councils like the immensely influential US Chamber of Commerce, which was formed out of local chambers from across the country in 1912. These organisations exploited the newly emerging Public Relations industry, launching a barrage of private enterprise propaganda, uninterrupted for more than a century, and still very healthy today. Peabody coal, for example, recently signed up one of the world’s PR giants, Burson-Marsteller, for a PR campaign to convince leaders that coal is the solution to poverty.
> Back in 1910 universal suffrage threatened the customary dominance of the business classes, and PR was an excellent solution. If workers were going to vote, they’d need the right advice. No-one expressed it better than Edward Bernays, Freud’s nephew, who is credited with founding the PR industry. Bernays was candid:
>> The conscious and intelligent manipulation of the... masses is an important element in democratic society (he wrote). Those who manipulate this unseen mechanism ... constitute an invisible government which is the true ruling power of our country… It is they who pull the wires which control the public mind.
> PR became an essential tool for business to consolidate its power right through the century, culminating in the 1970s project to “litter the world with free market think tanks”. By 2013, there were nearly 7,000 of these, all over the world; the vast majority were conservative, free market advocates, many on the libertarian fringe, and financed by big business. They cultivate a studied appearance of independence, though one think tank vice-president came clean. “There is no such thing as a disinterested think tanker,” he said. “Somebody always builds the tank, and it’s usually not Santa Claus or the Tooth Fairy.” Funding think tanks is always about “shaping and reshaping the climate of public opinion”.
-- https://www.abc.net.au/radionational/programs/ockhamsrazor/l...
Ah, bingo: here's a bit out of Higgs' book that discusses how the National Association of Manufacturers (NAM) campaign for the “American way” managed to get pro-business propaganda into the school curriculum in the 1930s, and lo and behold one of the early aims of the organisation is to fight against unionism:
> In 1895 the National Association of Manufacturers (NAM) was founded to lobby for business-friendly legislation and, under the leadership of David Perry, in 1903 it launched “a crusade against unionism.” [...]
> The NAM campaign for the “American way” was massive. It replicated Creel’s World War I model in establishing local cells, “Special Committees of Public Information,” which enlisted local Chambers of Commerce, Rotary Clubs, and churches, as well as lawyers, teachers, and local dealers of the appliances and cars made by the corporations. These committees of influential people were responsible for the regional face of NAM’s multifaceted “publicity program”; they funneled articles, features and films to newspapers, radio stations, and movie theatres; they sent speakers to the theatres as Creel had done, as well as to every local group of any sort (including women’s groups and what were then called “negro groups”); they distributed pamphlets and weekly bulletins to schools, clubs and libraries. Aware that the adult population was cynical about the corporate claim to “service,” they aimed specifically at schools where _Young America_, their weekly children’s magazine that portrayed capitalism as dedicated to looking after them and their communities, was sent to thousands of teachers, who used them in classroom assignments. _You and Industry_, a series of booklets written in simple language, linked individual prosperity to unregulated industry, and was distributed to public libraries everywhere. One million booklets were distributed every two weeks by the US Chamber of Commerce, which, along with the giant industrial corporations, was also involved in the campaign.