Cops are also allowed to lie in the US. Like "we have your fingerprints and DNA", even if it's not remotely true.

News programs perpetuate the idea that lie detectors work. Dateline, for example, will imply that refusing to take one is suspicious.

Truth doesn't matter. If you "get the charges through", you're successful, with little to no penalty for failure, as a LEO or prosecutor. Innocence and guilt are irrelevant. Justice, fair punishment, and rehabilitation are also not relevant. Success is measured by man-years in prison (or arrests for law enforcement). Usually there's room to just blame someone else if you do face scrutiny. Honestly, I think this is a result of greater cultural issue in the US (maybe other countries too, I just can't speak for the culture).

They get rewarded for successful convictions. And they always have the same defense - if those people aren't guilty, why are they confessing? Which is obviously stupid, if your choice is to serve 2 years now or risk getting 20 if the jury doesn't like you, then unfortunately the smart choice is to lie and take the 2 years. Jury system is also absolute nonsense and should be abolished.

The jury system is fine. Excessive use of plea bargains is the problem.

Jury system is very expensive. Including for defendant who is going to be bankrupt having to pay for defense.

The jury system has nothing to do with the costs defendants have to bear.

Because if everything went to trial the system would break down. I have read that 90% never go to trial instead there is some kind of plea bargain. If that practice got abolished the court system would need to grow a lot. It’s cheaper to throw innocent people into jail.