It occurs to me that, should extraterrestrial life exist - we might be more likely to be visited first by rules-flouting rogue individuals than by an official mission.
This also neatly explains problems like the "aliens have interstellar travel, but not spectroscopy and can be stopped by wooden doors" mentioned elsewhere in the comments --
A couple of good ol' boys off to deface a nature preserve (Earth to our aliens, the Nazca lines to our GOB's) by driving circles in it could do so today in a truck with active-torque differentials, wireless radiofrequency entry and activation, catalytic conversion of exhausts, an on-board diagnostic computer, turbocharging engine, liquid crystal display and a cmos camera, radar-based cruise control, lidar detector, GPS navigation relying on atomic-clock level timing precision..... without needing to know a thing about how even a single one of those components actually worked, and could be stopped by simple stone bollards.
This also neatly explains problems like the "aliens have interstellar travel, but not spectroscopy and can be stopped by wooden doors" mentioned elsewhere in the comments --
A couple of good ol' boys off to deface a nature preserve (Earth to our aliens, the Nazca lines to our GOB's) by driving circles in it could do so today in a truck with active-torque differentials, wireless radiofrequency entry and activation, catalytic conversion of exhausts, an on-board diagnostic computer, turbocharging engine, liquid crystal display and a cmos camera, radar-based cruise control, lidar detector, GPS navigation relying on atomic-clock level timing precision..... without needing to know a thing about how even a single one of those components actually worked, and could be stopped by simple stone bollards.