The US is not a jury-based system, but a plea-bargain-based system. Over over 94% of cases never go in front of a jury. [1] And while theoretically you can insist on your case going to trial, a few things will happen to you:
1. Your public defender will do everything possible to discourage you, because they don't have the resources to take you to trial.
2. As a consequence of not having resources, they will in fact be correct in discouraging you.
3. The prosecutor will charge you with far more counts, and a potential sentence that is much higher than what you'll get in a plea deal.
Note that the extra counts don't need to be provable. What they do is two things:
1. Add to your defense burden.
2. Put intense psychological pressure ("If I take this felony deal I get five years, but I might get TWENTY FIVE if I take this to trial and lose.")
If you can afford a good lawyer, the plea deal calculus works better, of course, since you now have a credible threat of taking a bad case to court and demolishing the prosecutor.
[1]: https://www.nytimes.com/2012/03/23/us/stronger-hand-for-judg...
You know, they’re doing you a ‘favour’ by avoiding the trial so long as you accept guilt.
laughs hysterically
In the real world, of course, they are used to throw the book at people with no ability to defend themselves.
The only circumstance that holds true is if you get a legit confession. But that confession still has to be fact-checked.
As for the rest, you cannot in any circumstance be obviously guilty unless you were an accomplice to that fact or you were captured after the fact. You would have to read minds to throw away the presumption of innocence, and even in those seemingly obvious circumstances there may be something else going on. So we have the trials.
Plea deals are exactly that - deals between you and the state to go to jail so you might not go to jail longer. They're not doing you a favour, because they have all the authority.
One would hope it would be easier to be found innocent when you are innocent - easier to produce evidence and proof of things that are true, and to produce convincingly honest testimony when you were being honest.
Edit: especially in a jury-based system it seems like it doesn't matter whether you're guilty or not, but whether the jury believes your story. In addition, many (most?) people who commit crimes do not necessarily think of themselves as criminals, though admittedly I got forgot from which source I got this.
Edit2: bottom line: why would influencing a jury suddenly stop working when you're guilty.