Yes, riding your bike in an urban area is often more or less as fast / convenient as driving. However, driving at 70mph vs biking at say 15mph, the time difference adds up very quickly once you are out in open country.

Not to mention that there is very well built infrastructure for driving, while biking often means going on that same infrastructure with a 50mph difference between you and the rest of the traffic. Basically if you are riding on a bike on a highway, you need to act as if you were invisible and expect that cars may actively try to kill you.