So do all countries. That's because poorer people tend to commit more crimes.
Unfortunately the United States incarcerate people 8 times more than Europe for example.
the United States "imprisons a larger percentage of its black population than South Africa did at the height of apartheid"
in 2008 the USA had around 24.7% of the world's 9.8 million prisoners
In fact, in 2008 the US
incarceration rate exceeded the average incarceration levels in the Soviet Union during the existence of the infamous Gulag system
So, yeah, singling out the US for unjustly jailing people is not random and perfectly justified by facts, if we don't cherry pick, and as you said, these are very disproportionately poor because they tend to commit more crime and because they can't afford good lawyers and because they can't afford good education.