Cars are replaceable. A few years ago I bought a Toyota. Then I got tired of it so I bought a BMW. No one has me locked in, I'm free to switch. So they have to

Cars are replaceable. A few years ago I bought a Toyota. Then I got tired of it so I bought a BMW. No one has me locked in, I'm free to switch. So they have to compete to keep me as a customer (or in the case of BMW to get me back, I was a former BMW driver).