I know it was a rhetorical question, but because of negative externalities. Same reason I can’t dump pollution in the river that runs through my property, because that polluted your property downstream.
That seems like a much better legal analogy. If anything, this should probably be considered search and seizure without a warrant. That would make the evidence inadmissible in court. Or we carve out searching DNA databases as outside of that amendment. That actually makes more sense to me as even your dna is no longer yours once it’s in the public domain on a hairbrush at the dumpster. IANAL.
