While the stock market has marched higher and higher, with some of those public companies making unprecedented profits and taking greater market share, there has been no or little trickledown effect for those that labor in our workforce. In fact, as reported by hbr.org, the labor's share of income has fallen from "… nearly 65% in the mid-1970s to below 57% in 2017," which succinctly reflects exactly what so many are suffering from, which is effectively the decline and stagnation of labor wages for many of those that are not highly placed within corporations, or skilled in the most lucrative fields of labor.
In addition, a significant part of this downfall, comes from the fact that private sector labor unions have declined precipitously since the 1970s, in which because there is strength in numbers, having no voice at the management table, means in principle, that wage demands will be effectively ignored by that management. This is why, laborers cannot do much of anything when they are laid off through the cutting of payrolls, or having their hours reduced for whatever reason at the convenience of such management, having their pay frozen and their benefits reduced, or directly suffering from the consequences of outsourcing of labor, the hiring of temporary labor that undercuts directly employed labor, and the subcontracting of jobs to outside agencies or other countries, in which the cost of that labor, is lower than maintaining workers already employed in that capacity.
All of these things add up, so that those that do not have money or assets which allows them to make money from investments such as the stock market, or housing, or by virtue of owning their own viable business, or other similar avenues, one can only make money through wage labor, and in absence of labor unions, or the ability to negotiate a reasonable pay package, will often mean settling for the prevailing wage in that sector, and thereby hope for the best.
One might think, that with unemployment being so low, that such would put pressure on wages in the sense that a shortage of laborers, typically necessitates an increase in compensation, since more companies must battle for the same employee base, but recent history has demonstrated that the correlation between low unemployment and thereby higher wages has disappeared. While there are many theories why this might be so, the most obvious reason is that a massive swath of Americans have no seat at the table of their employer, hence, they will acquiesce to a lower something, rather than a whole lot of nothing.
Since the mid-1970s, labor's share of income has fallen, which means, that management's share of income has risen, which is great for the profitability and bonuses of those most highly placed and favored within corporations but in aggregate, it is very bad for those that labor paycheck to paycheck, so that, what you see in America, is exactly what one would expect, a greater and greater division, between those that have and are connected to those that have, and those have not, and have no connections and no power.
Those that do not have a seat at the table of management, are unable to successfully negotiate better hours, better pay, better pay packages, better benefits, better job security, or much of better anything, and are in the unenviable position of simply, keeping their head down, questioning nothing, and staying out of trouble, just for the pleasure of having some gainful work and the very few dollars that come with it.