[ggm]

A point sometimes missed is that government bans on access to knives and aerosols aren't so much designed to actually make it "impossible" as to impose a social barrier, which demands active bypassing, and so clarifies the responsibility across the boundary.

Speeding isn't made impossible by speeding fines. It sets a civil penalty, non-compliance with the penalty in turn sets a criminal penalty, which in turn can lead to significant consequence.