A combination of several things. Tax rates that encouraged reinvestment into businesses through higher pay and R&D. Stronger or more heavily enforced anti-trust laws that meant tens of thousands of more middle management, board and CEO positions across the country per capita. Stronger unions were more able to use collective bargaining for better working conditions, though there power and ability was already falling due to the red scare.
Obviously there were also plenty of problems then as well. So there shouldn't be a 1-1 return. The US population has basically doubled since the mid 1950's, which few seems to mention regarding the current housing situation. The auto industry was busy ruining mass transit across the country, or already had. The red scare hurt unions. Racism has always been a problem for people who didn't win the genetic lottery of their generation.
In reference to OPs question, it was not a guilded age. There was one before, and we're in one now. That suggests that the pendulum needs to swing back towards that direction. Depending on how things go in the near future it could slow the swing towards guilded (if labor actually starts winning) or not (if children are made to be workers, women to be only mothers and the Biden admin blocks the teamsters like they did the rail strike). Our constitution is fairly explicit about how government should run, but is rather quiet about the economy. The people need policies that works for the people, and they will determine that.
Apologies for using generalities, but it's a random thread on the internet. It's not a great use of time to get into fine details, especially when late to a post, unless it gains interest.
It's pretty basic. At this point in time we can see what the promise of trickle down economics was, and we can see where the country is, compared to before, for the middle and lower classes. Even without blaming capitalism for this, we can see that giving wealth to the top fails more people than just paying people a decent wage.
The people claiming most to be pro-capitalist between the major two parties in the US are saying to stay the course and go even further.
I would like a return towards the capitalism of the 1950's-1970's. But that is generally considered to be socialist by the party seeking to keep going in the direction that has failed most Americans.
I would also like to emulate the whole of Western Europe in hopes of having a larger middle class as a by product of tax collection and spending, rather than paying for-profit entities, to get guaranteed services that support basic daily life. Capitalists do not want that because they cannot profit off of services provided by the government to anywhere near the same extent.
It's simple, the type and level of capitalism currently in place in America makes life unnecessarily difficult for the citizens of America.
Co-ops can be capitalistic and are capable of functioning under capitalism, but they would also work much the same under any market economy. Decisions and would be profits are democratized/socialized.