We don't have juries because they are smarter or more fair or more just on average than a judge. We have juries entirely due to the concept of jury nullification. It's a formalization of the concept the founders sometimes expressed where "Yes I did it, but that doesn't mean I should go to jail" is an intended outcome. It's explicitly that Justice isn't the same as "follow the letter of the law".
Arkansas is one of the least educated states in the US and one of the poorest. So, yea, there are a lot of systemic issues there.
Who says that's the case? US courts are overloaded and public defenders are massively overloaded.
Most people can't afford to hire a good lawyer, and a (let's say) 10% chance of years in prison isn't worth gambling versus a plea deal to them. Prosecutors know this, file massive scary charges, and motivate people to settle regardless of innocence or guilt.