That's fine,but all electric vehicles require a tiny fraction of the maintenance that petrol powered, oil lubricated ones do. This is a problem for the future of maintenance shops.
You overstate the maintenace required on modern internal combustion engines. Most will go 100,000 miles with nothing but oil changes. Oil changes are often a loss leader for maintenance shops. Tesla cars will still need tires, brakes (though maybe less often thanks to regenerative braking taking the load off of standard friction brake pads), air conditioning service, alignments and other suspension work, etc.
That's certainly why they would dislike Tesla in particular, and perhaps why they might spitefully lobby against Tesla selling direct to the consumer, but otherwise I don't think that independent shops should really care about the dealership situation one way or the other.