There are two people involved in this scenario: the car driver and the car manufacturer. For the car driver, physical buttons are simpler (less cognitive load and safer to operate). For the car manufacturer, a single tablet is simpler (less manufacturing complexity and cheaper).

EDIT. I forgot with the Right to Repair issue, there is a third person, the neighborhood general mechanic. With physical controls, the mechanic is more likely to be able to repair the broken switch/electrical relay. With the tablet, the mechanic cannot.