Because SOD has more investigative inputs than just the NSA, and also because they are not required to track only metadata for foreigners. More mundane (and pe

Because SOD has more investigative inputs than just the NSA, and also because they are not required to track only metadata for foreigners. More mundane (and perhaps more likely) is that the source data for that kind of tip comes from wiretaps from existing open investigations. You might not get probable cause for a search based on the wiretap data alone, so SOD gets the local cops to alert on the car instead and "start" the follow-up investigation.