It's "search satisfaction", I think. People expect to look for (and dismiss) the obvious stuff.
This is similar to the notion that having the TSA check for liquids at airports is dangerous, because when they find a bottle of shampoo, they stop looking for other stuff.
This is similar to the notion that having the TSA check for liquids at airports is dangerous, because when they find a bottle of shampoo, they stop looking for other stuff.