That's unequivocally false.

For example: there are many legal concepts which are not a crime to disobey (and therefore there is no criminal reason for police to be involved) and/or it is not in the jurisdiction of any police force.

Possibly that's true in the US, but it's completely false in many other parts of the world.

In England there's a bunch of stuff that has no police involvement. Debt or tenancy are the two biggest areas.

Not all legal constructs are practical, possible, or necessary to be enforced. And even for those that are enforced, not all necessarily need to be enforced by physical force.