I don't know how it works in England, which could very well have substantially different labor laws, but in many major cities in the US the cabbies either rent

I don't know how it works in England, which could very well have substantially different labor laws, but in many major cities in the US the cabbies either rent the vehicle or rent the taxi medallion from the cab company. It's kind of like how the sometimes people who deliver newspapers technically buy those newspapers from the newspaper and then collect the delivery fee.