We judge how likely something is by how easily we can recall it.
Many people fear flying more than driving, even though flying is safer per kilometer traveled. We judge how likely an event is by how easily we can recall examples of it, not by the actual statistics.
A plane crash gets massive media coverage and stays etched in memory; thousands of car accidents, far more frequent, almost never get individual coverage. That uneven availability in memory distorts our real perception of risk, even when the data says otherwise.
Recalling an example easily feels like evidence that it's frequent, even though how easy it is to recall depends on other factors (how recent, vivid, or heavily covered by media it was), not on its actual probability.
Source: Tversky, A. & Kahneman, D. (1973). Availability: A Heuristic for Judging Frequency and Probability. Cognitive Psychology, 5(2), 207-232.
Communicating real risks (health, financial, safety) competes against vivid examples people already have in memory, often unrepresentative ones. Aggregate data rarely wins that battle if it's presented alone, without an equally memorable example.
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