No manufacturers allow a 7 day-Test Drive to look it over policy. Some independent dealerships with tons of cars in stock may do so, however never for an aspirational car with limited supply.
It is different buying factory direct than from a dealership.
Ford sells directly to their dealships. No test drives, look overs, walk arounds, or sit insides allowed. They take what Ford ships them and they deal with any issues once they have taken ownership.
With factory direct you do not have that middleman dealership, adding costs and value to customers.
When you order a Corvette from GM, you place your deposit and the dealership will tell you when it comes in. Current buyers have been waiting over a year, with many delays over that time. They will have it all shined up in the lot, but arrange payment, insurance, financing etc prior to letting you drive your car home.
Picky Tesla customers want to hyper inspect their cars prior to accepting delivery. They obsess over forum complaints and want to make sure their vehicles are absolutely perfect in every way, or will instantly reject any car with any flaw. Will use high definition cameras with specialized lights to peer into crevices for internal flaws, use insturments to go over every fender to determine paint thickness at many points, go over interiors for any smudge, use gauges to inspect every panel gap and compare every left to every right side measurement.
Relatively few mass produced vehicles can stand up to such high levels of expectation, so Tesla would be stuck with thousands of rejected vehicles every day around the World.
Their current policy is that customers will accept their cars as delivered. Any out of spec issues are to be addressed after delivery by your friendly local service center. Obvious quality defects are grounds for immediate rejection on delivery, mainly they expect customers to accept vehicles as presented.
Of course customers want their cars to be of high quality, and be pleased with their purchases, but some are so picky that no production car will reach their very high standards of perfection.
Tesla is under pressure to deliver a thousand cars a day. Buyers are only really concerned about the one specific car that they are eager to drive home with pride.