It also seems Tesla has also just being fined by S Korea for not being upfront about the 50% reduction in range when we get severe cold weather. Surely the display warns you of these 2 items automatically?
It isn't possible to directly warn you of something that doesn't exist.
Yes, EV batteries are less efficient in cold weather and range can drop by up to 20% depending on how cold it is. Tesla's like all EVs can be fitted with a heat pump which helps combat this by about 10%. However in extreme cold (-15c or below), even the heat pump will struggle, and Tesla has had an issue with the pumps on the 3 and Y which are failing. They fixed the issue once, but it has recurred.
The figure of 50% is a 50% reduction based on
how they are advertised online. Everyone knows that the range stated by manufacturers is as accurate as the MPG quoted on ICE cars.
What the car will do is adjust your predicted mileage and tell you how many miles you are doing per kwh. It will then point you to a charger when it is needed. Range changes hugely based on how and where you are driving, the heat / cold issue is just another variable.