So let's say that's 10 cars and 200 bikes (being generous, usually cars have only one person in them, and also bikes esp. with children in biking-heavy countrie

So let's say that's 10 cars and 200 bikes (being generous, usually cars have only one person in them, and also bikes esp. with children in biking-heavy countries have more than one person carried by them). If they are evenly spaced, there will be a car every 0.1 miles - and each car is going 100mph according to this thought experiment. This gives 3.6 seconds to cross between 100 mph cars that probably won't swerve to avoid you and may careen out of control if they do. Meanwhile, there is a bike every 26.4 feet, and you have 1.8 seconds to cross. 10 MPH is speedy for a bike, but they have to only slightly adjust to avoid hitting you if you make a mistake (and are about 1/5th the width if not less). I'll take the bikes!