Most criminal cases resolve with plea deals. Many people do not have the time, money, or favorable evidence to make proceeding to trial practical. Plus, going to trial is always a gamble. Sure, at trial, you may be found not guilty and have the case dismissed. However, if you are found guilty at trial, you will be exposed to the full sentencing range of each offense which you are convicted. The benefit of a plea deal is you know with a degree of certainty what the sentence will be, or at least what the sentencing range will be. Having this certainty is valuable for most people.
Also, in almost every case there is just enough evidence against the accused that the prosecutor will be able to secure a conviction. If there wasn’t enough evidence, charges most likely would not have even be brought against the accused. So, given the fact there is almost always enough evidence for the prosecutor to prove guilt at trial, the accused can take advantage of the prosecutor’s desire to resolve the case without a trial.
The prosecutor is paid a salary and is not paid any more for proceeding to trial on a case. However, the effort and work the prosecutor needs to endure to prepare and prosecute a case at trial is a lot compared to the average day to day work of being a prosecutor. Plus, going to trial takes a lot of TIME. This is something the prosecutor does not have. The prosecutor will often offer a plea deal that benefits both parties. By making a favorable offer to the accused, the prosecutor hopes he or she will not have to proceed to trial to get a conviction. The accused hopes to receive a lighter sentence.