Not all legal systems put the burden of proof on the accuser. In fact, many legal systems have indefinite detentions, in which the government effectively imprisons a suspect, sometimes for months at a time. To take it a step further, the plea-bargain system of the USA, is really just a method to skip the entire legal process. After all, proving guilt is expensive, so why not just strong-arm a suspect into confessing? It also has the benefit of holding someone responsible for an injustice, even if the actual perpetrator cannot be found. By my personal standards, this is a corrupt system, but by the standards of the legal stratum of society, those KPIs look _solid_.

By contrast, in Germany (IIRC), false confessions are _illegal_, meaning that objective evidence is required.

Many legal systems follow the principle of "innocent until proven guilty", but also have many "escape hatches" that let them side-step the actual process that is supposed to guarantee that ideal principle.

EDIT: And that is just modern society. Past societies have had trial by ordeal and trial by combat, neither of which has anything to do with proof and evidence. Many such archaic proof procedures survive in modern legal systems, in a modernized and bureaucratized way. In some sense, modern trials are a test of who has the more expensive attorney (as opposed to who has a more skilled champion or combatant).