What's more mobile than a bike? A car.

A car can go 3 times faster, there's more routes for cars that are inaccessible by bike (freeways, interstates), a car still goes nearly as fast in the winter as it does in the summer, and does not require changing clothes for longer rides or taking a shower at either end (some days are so hot you'll sweat standing still - a car has an air conditioner) and allows you to carry stuff without pre-planning and at the same speed you go without carrying stuff.

Now you don't get any exercise in a car, a car is rather expensive, you have more of a headache with parking in the city, and you might just enjoy biking more. But in the context of looking for a job, there's no doubt (yeah, I'm sure there's some sort of special situation kind of exception, but in general) that a car let's you travel farther to find a job than you would be able to (reasonably) by bike, and thus it's more mobile.