>By that I mean video evidence, financial transactions, text messages, emails, cell phones tower pings for location
Yes, you are right, the majority of criminal convictions at trial are based on physical evidence (of course 9 out of 10 cased do not go to trial). But none of that evidence comes in without a witness that can introduce it.
So perhaps not an eyewitness to the crime itself, but a mandatory witness to introduce the "hard evidence". So for example take any DUI, before any video of the suspect or breathalyzer evidence can be introduced the officer needs to testify to the facts of the initial stop, then a witness needs to introduce the breathalyzer (make, model, has is been calibrated regularly, is/was the officer properly trained, did the test results get handled through the proper chain of custody, etc...).
>Even in your example, the video is what identified the suspect and lead to arrest not eye witnesses.
A video can't be introduced without a witness (now they don't need an eyewitness to the events depicted on camera, the store manager/records custodian will generally get the video in, but a good defense attorney might get it thrown out, so the eyewitness to the abduction becomes the key evidence in the case itself).
This is why "red-light cameras" failed constitutionality tests in many cases, because many jurisdictions tried to introduce the video without a witness...which violates the defendant's right to cross examine.
Or take the OJ case...all the physical evidence in the world from bodied, to murder weapon, to bloody glove...and no conviction.