You're right, I left some pieces out for brevity. To elaborate, they were not picking up the Tesla from Austin and started for San Antonio straight away. They were vacationing, and as all vacationers do, they went sightseeing, eating out etc. and by the time set off for San Antonio, were not sure if they'll make it, then charging was an issue. Multiple factors combined to convince them that the Tesla is no good when you don't have a plan.

I don't know nearly enough about electric cars, but I was under the impression their battery performance severely drops off in extreme heat and cold. On an extremely hot day (say 112F/44C) what is the maximum distance which you can traverse?

The older Tesla's do lose up to 30% range in the cold, but all the currently sold Teslas have heat pumps which largely fixed that problem. It's true that you won't get your rated range unless you're driving on the level and not going faster than 55, but you'll get more than enough range to get between Superchargers on road trips or to putter around town all day. If you want to putter around town all day and then leave for a road trip, you better super charge in between.

The numbers I’ve seen quoted are in the neighborhood of 20-30 percent, but that’s only really for cold weather. Tesla batteries are actively cooled, so there shouldn’t be a significant performance decrease other than the power draw from the AC unit in the cabin.

Even if there were a 50% loss in efficiency the car should still be able to travel over 150 miles, the notion that the weather would drop the range to less than 80 miles is absurd.

I don't know the answer, mainly because there would be a lot of variables starting with the battery pack option one purchased, but it will for sure be a considerably larger number than 80.