Because global warming is a threat orders of magnitude greater than aviation-based terrorism, to the extent that the TSA discourages flying it makes us all safer.
Per traveler-mile, commercial aviation is radically worse than automobiles, even if they're all only carrying the driver. Net, it would be a reduction in emissions for everyone to drive instead.
Where are you getting that from? Airbus claims the A380 gets 3L/100km per passenger when fully loaded[1], which is better than all but the must fuel-efficient passenger cars. Even the Concorde got ~17L/100km, putting it in line with large pickups.
You're basing your calculation on one of the densest possible configurations of the aircraft — one denser than almost every production deployment. Only one actual seat configuration exceeds your Airbus press release's density, offered by Emirates, and is nearly all economy class. Everyone else's offerings are from ~5-40% less dense, yielding comparable decreases in efficiency. [1] So, sure, the largest, most efficient jumbo we currently make has an absolute passenger-mile emissions rate lower than many cars — when it's carrying as many people as possible.
You're also ignoring the fact that emissions at altitude have an increased impact. "For perspective, per passenger a typical economy-class New York to Los Angeles round trip produces about 715 kg (1574 lb) of CO₂ (but is equivalent to 1,917 kg (4,230 lb) of CO₂ when the high altitude "climatic forcing" effect is taken into account)." [2] Even the most fuel-efficient car isn't dumping tons of NOx at cruising altitude, inducing excess ozone formation.
"taken as a whole, the systems used to move illegal drugs around the world comprise a logistics network likely bigger than Amazon, FedEx, and UPS combined."
