You could argue the opposite:

Since WWII, western countries have seen an incredible growth of wealth. This growth of wealth translated to a huge improvement of leaving condition for the masses, which means that said wealth was reasonably well distributed and government knowingly or unknowingly made this happen.

By contrast, the XIXth century, despite growth, the average life conditions worsened significantly for worker leading, This lead to ideologies like Anarchism and Communism.

Why did this wealth was somewhat correctly distributed? Basically the two World Wars and the Great Depression, In Europe, the cost of the 2 wars and the inflation after them basically destroyed a huge chunk of the wealthier classes living of their accumulated money (rentier). In the US, the Great Depression and WWII lead to decisions like a tax rate of more than 90% for the wealthier, which lead to keep in check inequalities during the 40ies, 50ies and 60ies.

All this happen because of strong government basically stating: the interest of the whole is not the sum of individual interests.

It also happened because at the same time, an incredible amount of "new wealth" was being created in such a short span, this kind of growth rate was unprecedented in human history, it was easy and even somewhat natural to distribute more in this situation. These two factors combined to reduce inequality and improve living condition significantly.

The issue is that inequalities in revenue were still occurring. Slowly capital was becoming concentrated again. Which lead to the slow reconstitution of a strong wealthy class concentrating capital. This strengthening happened progressively by buying media channels, donating to politicians or even becoming one and lobbying strongly for favorable laws. This lead to policies/laws in the interest of this smaller group reinforcing this concentration. Basically, it's stating the obvious: there is a correlation between wealth and political power.

Also, since the 70ies, there was a strong slowdown in radical technical improvements and deployments, leading to less "new" wealth being available.

Now we are basically returning to a repartition of wealth as seen the XIXth century (albeit with far more wealth available).

It's a slow process, almost organic, the wealthier classes are not an homogeneous core, they have different and conflicting interests, but as a whole it's able to push in a given direction. The general population is far bigger, and also have conflicting interests, is even less homogeneous and doesn't have wealth, so it's not able to push as efficiently for the common interest.

It has nothing to do directly with governments. Strong governments actually helped a lot in reducing inequalities. But there is a limit to their action.

Maybe, now, what we need is a more radical way to redistribute wealth by for example an exceptional and significant tax on capital, and do it from time to time to re-balance our societies. Otherwise, long term, it will happen in this form or another: Revolution (a common occurrence in revolutions is the burning of debt files and archives), but I'm not convinced it's the good way forward given all the Chaos it will entail.