Plot Technology

High technology (or magic) available to characters never seems to trickle down to the populace. In particular, if a villain is in possession of a weapon which would be worth millions to the Pentagon, why would he limit himself to robbing banks with it? This especially applies to one-shot enemies on Speculative Fiction series with amazing inventions that have never been seen before -- and are never seen again, unless that villain recurs. One suspect is the short half-life of the necessary Plotonium-186 required to power this type of technology.

See also No Plans, No Prototype, No Backup, Cut Lex Luthor a Check, Reed Richards Is Useless.

Comic Books

 * This was the original rationale for changing Superman villain Lex Luthor from a Mad Scientist to a Corrupt Corporate Executive.
 * The villain Bloodsport had a teleporter capable of summoning weapons from a cache both the weapons and the teleporter were supplied by the corporate Lex Luthor who could surely have made a fortune selling this stuff to the military.
 * The Four in Planetary are described as having stockpiles of technology like this. Which they intentionally keep to themselves. The Four are also shown to be plotting to sell mankind to alien monsters, then leave their Earth for some other world to conquer. All that ultra-tech would come in pretty handy. Logical, really.
 * After they're beaten, the Planetary Group switches from fighting them to distributing all that ultra-tech. Utopia ensues.
 * Iron Man once went on a campaign to destroy all the armor suits that he knew were stolen from him or based on his old designs.
 * There are shades of this in Iron Man 2.
 * After the registration act, the New Warriors were reformed by members with stolen parts and prototypes of devices used by other Marvel characters. A Doc Ock harness, Scarlet Spider Web shooters, and a patch work Iron Man were notable and they operated out of a deserted villain's base. The group did eat up some funds keeping everything working however.
 * First Lampshaded, then subverted by Starman. When Jack Knight agrees to take on the mantle of Starman, he castigates his father for having had this incredible technology for years, but never doing anything with it except fighting supervillains, and only agrees to be Starman if his father works on the civilian applications. At the end of the series, he delivers. (Though these were undone to fit him into The DCU.)

Web Comics

 * A Miracle of Science throws a spin on this by having "Science-Related Memetic Disorder" as a plot device, and after the Mad Scientist is treated for said disorder (and prevented from doing stereotypical mad science activities, another parody AMOS uses), the "Plot Tech" devices can be used by the general population. For example, early in the series the Lunar Cannons - remarkably similar to those used in Final Fantasy VIII - were introduced as made by the first Mad Scientist.
 * In Sluggy Freelance there seem to be a handful of Mad Scientists with extremely advanced technology, but at most they share their inventions with one corporation, not the entire world. Riff has tried selling his inventions on occasion, but they tend to be too dangerous for most people to handle.

Literature

 * Justified in the Wild Cards series, wherein some examples of amazingly advanced technology appear to exist (independently of things brought by genuinely more advanced aliens); however, it turns out that the ability to build such machines is among the powers granted to some by the Wild Card virus. Most such devices will only work for the Aces who build them -- they're not really working machines, but a form of Magic Feather -- while the exceptions can't be reproduced by engineers whose brains haven't been rewired by an alien genetic weapon.

Film

 * In The Incredibles,.

Western Animation

 * It seems in Gargoyles, there is a level of super-technology only available to billionaires; as David Xanatos and others have access to airships, robots, etc.
 * This is probably justified by having super-technology be so expensive that only billionaires could afford it. One is mentioned as having risked bankrupting his company making said airship.
 * That seems like Truth in Television, as most shiny new technology costs millions (on the low side) to develop.
 * Gargoyles also averts this and justifies Family-Friendly Firearms? in one swoop by having an arms shipment get hijacked and distributed on the black market.
 * All over the place in Kim Possible, especially with her Mad Scientist Arch Enemy Dr. Drakken and Gadgeteer Genius Mission Control Wade. With only a few exceptions, many of their creations appear once and never again.