20mph is an interesting speed since a electric bike here in Sweden would be illegal if it reached those speeds. And as a owner of a legal electric bike I can say that regular bikes do not pass by at 20mph in the city. Even 15mph, which happens to be the legal max speed for a electric bike, would be unusual to see for a regular bike. Of course an open road would be different but pedestrian that walk against traffic there has a much bigger problem than the few cyclists that can reach 20mph unassisted.
Lethality is not the only criteria but accidents between pedestrians and cyclist is exceptional rare in relation to all the fear people feel towards cyclists. The opposite is true for cars. Ironically the fear towards cyclists seems to go down during winter (since bike lanes tend to be more free from snow and ice than the side walks) so during the time when the bike lane is the most dangerous it is also the time when most people are walking on them. There is thus a strong correlation between fear of bikes and lack of conveniences.
Lethality is not the only criteria but accidents between pedestrians and cyclist is exceptional rare in relation to all the fear people feel towards cyclists. The opposite is true for cars. Ironically the fear towards cyclists seems to go down during winter (since bike lanes tend to be more free from snow and ice than the side walks) so during the time when the bike lane is the most dangerous it is also the time when most people are walking on them. There is thus a strong correlation between fear of bikes and lack of conveniences.