The scene
Sunday evening, on the sofa
Someone scrolls through Facebook and sees the new SUV from the dealership down the road. They tap "Sign up". Their name, email and phone number are already filled in. They pick Sunday for the test drive and send. It took ten seconds.
Had they landed on the website, they would have waited for the page, looked for the form and typed five fields with one thumb. And the first incoming call would have been enough to stop everything.