You can assume "the system is lazy".

In practice, "the system" is a lot of humans. The police in rural Canada aren't used to challenging the word of Wisconsin police. Police and prosecutors need to have an incredible discipline to hear "we have a suspect in your community who preyed on a pre-pubescent girl in our neighborhood" and remain neutral and dispassionate during the investigation.

The stupid part is that the prosecution is supposed to be competent and ethical (but one of those failed). Then the defense attorney is supposed to be competent and ethical (but one of those failed). Presumably the jury got access to all of the facts of the case and simply ignored the lack of evidence tying the defendant to the offending Kik account. A chain of 3 errors shouldn't happen if everybody is diligent, but in practice "won't somebody think of the children?!?" Turns off cognitive skepticism and encourages moral panic.