OOOHHH!!! I know this one!!!
This is a DOT (Department of Transportation) thing here in America. When a manufacturer produces a vehicle there are certain guidelines they need to follow for various classes of vehicles. An automobile manufacturer cannot offer or produce a "Passenger Vehicle" with what we call "Factory Tint", "Privacy Glass" or "Smoked Glass". This passes the regulation of how dark you can legally have your windows to the state level.
BUT, when the manufacturer produces a "Truck" or an "SUV" the rules are different. A vehicle produced with a "truck chassis" can have "factory smoked glass" from the manufacturer. However the only windows the manufacturer can choose to add this feature are from the A-Pillars and back. These windows aren't even considered to be used by the driver for "trucks". Think of the panel vans with no windows at all. The manufacturer cannot have any tinting on the front doors or windshield no matter the vehicle class. Even though the Teslas have the uni-body "chassis", they still have to categorize their vehicles. So, they call the Model X a "Truck" and are probably going to do the same for the Model Y. With the Model Y and Model X being called a "truck", they will have to follow the guidelines in place for a truck vs a passenger car. You can have a tow package installed legally, and be able to tow heavier loads and trailers. Yes, you can legally add a tow package to other passenger cars too, but there are legal limits on how heavy you tow.
The biggest head scratcher for me is the Subaru Impreza vs the Subaru Crosstrek. They are nearly identical, but the Crosstrek is considered a small SUV and the Impreza is a passenger vehicle. lol.
I hope this helps.
