Safety Devices That Do Not Protect

Glenn Reynolds points to an example:

Reading Tom Vanderbilt’s latest book, Traffic: Why We Drive the Way We Do (and What It Says About Us), I was struck by a recurring theme: Making things safer may actually make them more dangerous. I wonder if it’s a lesson that also applies off the road.

Vanderbilt describes driving along a narrow, twisting road in Spain, where he navigated hairpin turns with few guardrails or warning signs over steep drop-offs. The result: “I drove as if my life depended on it.” But when he reached a four-lane highway with gentle curves, good visibility and little traffic, “I just about fell asleep and ran off the road ... Lulled by safety, I’d acted more dangerously.”

………

Famed Dutch traffic engineer Hans Monderman once said: “When you treat people like idiots, they’ll behave like that.” Monderman’s philosophy is, instead, to design things so that people are called on to use their wits—at least within limits. When that happens, things often wind up safer.

Question: If externally-supplied safety devices make people less safe, what does that imply about handing contraceptives to high-school students? (Note: When I say “externally-supplied safety devices,” that's in contrast to safety devices sought by the people involved. The latter are unlikely to cause reckless behavior and might be associated with prudent behavior.)

ObSF: The title of this post is the opening line of The Vortex Blaster by Doc Smith.

Addendum: There appears to be at least one counterexample.