I always have trouble imagining examples of this kind of evidence that criminals were previously utterly unable to hide but can now do it easily using encryptio

I always have trouble imagining examples of this kind of evidence that criminals were previously utterly unable to hide but can now do it easily using encryption. It seems any kind of evidence could had just been shredded and burned in times past or hidden in an obscure, physical safe that no one knows about. If anything, the digital age had made the location of evidence more obvious and even produced entirely new kinds of evidence (traffic and connection logs, emails, etc). It seems to me that law enforcement is simply pining for the fjords of a very short time span in human history when ample digital information co-existed with the lack of widely available cryptographic systems.