[mikhailfranco]

Modern traffic radars have enough spatial and velocity resolution to apply a tailgating measurement. There are existing speed camera systems that can detect and ticket vehicles for tailgating, after a manual review of video and telemetry data (often just a quick glance and mouse click from a police officer).

There are relatively few jurisdictions that have a concrete quantitative definition of tailgating. So it's not yet widespread, but law enforcement certainly has the option available now.