The desire for strict VIN and sequence order seems like an issue particular to Signature buyers, who are more sensitive than others perhaps to sequence and VIN order. It doesn't make sense for Tesla to optimise their production line process for something that concerns a relatively small portion of total buyers, especially if it entails significant extra cost. In Europe, most cars are sold on a build to order basis, with a typical delivery delay of around 6 weeks. Once the car is built, they deliver it to the dealer and they call you. That's it. If it happened to take 18 weeks instead of 6, don't expect an explanation or an apology. Efficiently running a factory is hard, so much the more so during a ramp up like Tesla is going through. Everyone appreciates the commitment to Tesla that Signature buyers have made, but looking from the outside many of these issues seem small in the grand scheme of things.
That said, Jkam has every right to be upset, and I would be coming out of my skin if I were in his shoes.