Displaying the remaining battery in ‘miles’ is certainly misleading, but it probably helps some people understand vaguely what they can expect. The trouble is the car can’t get past the physics. If more work is to be done, it takes more energy. Things like A/C, vehicle speed, outdoor temperature, heat use, tire pressure and all that make significant impacts in the energy the car takes to travel.
If you turn the heat on and never drive anywhere, you can kill the battery to 0% in about a day without having driven a single mile. Now, under absolute ideal conditions at absurdly unrealistic low speeds, downhill, you can travel probably ~1000 miles or more. This is the same story as any vehicle irrespective of how it’s powered. But it’s more noticeable in an EV since people tend to be hyper sensitive to the remaining range.
You can get the rated range, but it’s going to be in fair to good conditions and speeds in the 50-60ish range. Shorter trips will also kill range as the vehicle stays ‘awake’ after the trip to condition the battery. So if you stack a bunch of small trips together with long breaks between them, expect around 1/2 the rated range. But on the highway, the range is quite good. Still, in practice it’s unlikely anyone will ever practically drive 310 miles on an AWD. That’s running from 100% to 0% under nominal conditions. Tesla doesn’t recommend charging to 100% regularly, and I don’t know anyone that wants to run down to 0%. So the everyday range is more like ~200 comfortable miles. It absolutely can be much higher or much lower depending on conditions though. Driving through deep snow in very cold weather with the heat cranked, you’d be lucky to do 100 miles.