I do not know why people would lie about what they have seen. Eyewitnesses usually do not show up to court if they are scared for their life. Usually people do not like when horrific things happen right in front of them and will tell the truth. I believe eyewitnesses can be trusted for the most part in court.
There is a lot of evidence which shows that eyewitnesses are not recordings that are played back, but are suggestible and somewhat unreliable. This means that they cannot be trusted alone as the sole basis of a case, but are still valid as part of a convergence of evidence. We cannot be 100% certain in court, but eyewitnesses may be able to make a case of reasonable doubt into one where there is no reasonable doubt.
Eyewitnesses can be trusted in courts across the land. They do not have a reason to lie and they want to see the right person punished for the crime. No one wants to see the wrong person punished for a crime that someone else committed. They will always be good to use.
I definitely think that some eyewitnesses can be trusted in courts. Even though I do not think they are the best sources of evidence for cases, I think that some of them can be very helpful. But it usually depends on the credibility of the eyewitness themselves whether juries agree.
Eyewitnesses can not and should not be the sole evidence to convict in a court. Eyewitnesses are often unreliable, either for innocent reasons or more sinister ones. If there is evidence to back up the witnesses statement or the witness was with the defendant for a long period of time, it can be trusted. Despite this, usually most people who witness a crime can get small or large details wrong, and as a result eyewitnesses can not be trusted.