> I think this is a kind of ‘broken window’ fallacy - ie unless there is a genuine service being offered then it’s kind of like requiring gardeners to use toe-clippers (ie the local economy are paying extra to hire people to do basically nothing).

I'm not going to argue with you as to whether or not the theory behind it is correct (my feelings on the subject are complicated), but I will point out that there's a major political movement in this country to 'keep it local', that has varying degrees of support in varying levels of government. Regardless of whether or not this desire is correct, whether its organic, or whether its simply manufactured through propaganda - it's present, and it gets acted upon.

> Tesla offers a trade-in program so that appears to be similar in some respects?

Which I address in point #4 - at the point where they start doing a major amount of business in trade-ins, they start looking like... A corporate-owned dealership, as opposed to a franchised one. A lot of the cost savings of 'show room-only' stores go away when you start having to deal with used inventory, scheduling test-drives, fixing cars in your dealership garage, etc.

Obviously, when they were first getting started, their used market was tiny, and none of those business needs/costs were present. But as their cars age/if they ever manage to successfully sell more models/if they somehow manage to capture a major chunk of the overall auto market, their 'stores' will have to offer pretty much every service that a traditional dealership does.