Re: plea deals. Most people don't know that plea deals are very common. Over 90% of convictions come from plea deals.
It's not just that lawyers are expensive and court is risky. Court also takes fucking forever. Somewhere along the way, a right to a speedy trial has been lost. People have jobs they have to get back to, families they have to provide for. The plea deal is often a way out right now, with the tradeoff of having a conviction.
Even if you're 100% innocent, it's often the better financial choice to just... take a guilty plea. The end result is we can't really say, for sure, how many convictions are actually guilty people.
The calculus gets even more complicated when we consider race. If you're a large black man, are you really going to want to take the chance in trial? If you're a meek white woman, you might be more inclined.