Outdoors are generally not protected by right to privacy, even if on private property.

Someone standing in their own front lawn can be recorded with both video and audio without their consent.

This is what makes it legal to record police.

Yeah, that's mostly true, but the front porch of a home is part of the home for 4th amendment purposes. Police obtaining warrant-less access to your front porch would violate this.

If someone is out on the street, it can still be illegal depending on the state. In new york, for example, the definition of illegal eavesdropping includes:

"Mechanical overhearing of a conversation" means the intentional overhearing or recording of a conversation or discussion, without the consent of at least one party thereto, by a person not present thereat, by means of any instrument, device or equipment.

There's no no stipulation about location.