It may be that Tesla can save several hundred $ per car by not including a tow hitch on initial production.
Tow hitch will add lots of extra weight and cost. Not including it as as standard item might also enable a higher EPA e rating as well.
Will simplify production and be one less thing to worry about on production ramp.
Then they could add towing capacity at a later date, as a demand lever, to get a fresh batch of orders.
Not saying that this is the case, and the tow package might be coming as a standard item, right out of the gate, but it is more usual for a manufacturer to offer a factory tow package as an extra cost option for buyers.
It may be that a significant tow package will entail additional motor cooling, suspension enhancements, sway controller software, larger tires/wheels etc.
Tow package might also require air suspension, or some other way to adjust ride height for the additional load on the rear.
Believe that is one of the reasons that the Model X changed away from coil springs as standard, and made adjustable air suspension a standard item when the tow package also became standard.
Comprimise might be a light duty standard tow hitch, useful for small utility trailers, bike/accessory racks etc. (best guess)