These customers own expensive cars - or at least, cars that were expensive when they were new. The car might now be ten years old or more, and the owner bought it used. They want a prestige marque, but the customer does not have the money to buy a new prestige car. So they are looking to save on service.
All the time I see cars with expensive names - BMW, Mercedes Benz - broken down on the side of the road, while old Hondas and Toyotas keep cruising by. Those are the customers for this shop: they spent all their money buying an expensive used car, and now they can't afford to maintain it and fix looming problems; meanwhile the Toyota or Hyundai driver gets maintenance and maybe even takes it to the dealer for it.
A mechanic like this can't afford to hire someone to answer the phone. Such a person is expensive, and these customers want rock-bottom prices despite the car being expensive. So a chatbot is good enough and better than nothing.