What you're saying is how people generally think the law works, but it's not how it works in practice. This is easily illustrated with possession of drug paraphernalia charges. There's two types of possession, actual and constructive - but both face the exact same charge. Constructive just means something like 'could be reasonably accessed.'
So imagine you're in a car, get pulled over, it smells of weed so the cop executes a search, and he finds a pipe in the glove compartment. You're getting arrested for PDP there 100%. Even if it genuinely wasn't yours, you stand very little chance of acquittal. Beyond a reasonable doubt doesn't mean 'is there some other viable explanation' because there literally always is. It means is it reasonably likely that one of these other explanations is what really happened.
