[vkou]

> Government surveillance is supposed to require a warrant.

No, invasive government surveillance is supposed to require a warrant. Invasive is defined as a search of your 'person, house, papers, or effects'.

A third party's records on you aren't your person, house, papers, or effects. They are records concerning you, but they are not your records.

The government (just like every other government in the world) doesn't need a warrant to receive a tip, to ask your neighbour if they want to volunteer/sell any information about you, or to surveil you when you go about your public activities.

I'm sure you didn't consent to be the subject of that tip, or to your neighbour snitching on you. That still doesn't mean that it's not a legitimate form of surveillance.