I'm now rereading old SF that I first read 40-to-50 years ago. I don't think I've found a single example where an SF author actually got tech right.
As I recall, his communication satellite depiction included humans living on it full time to keep it running. Also not quite how it turned out.
I have the utmost respect for him, but he was not immune to getting the future wrong like other science fiction authors.
Luckily tech improved a lot, so now many more things are possible for much less capitol.
>> An "artificial satellite" at the correct distance from the earth would make one revolution every 24 hours; i.e., it would remain stationary above the same spot and would be within optical range of nearly half the earth's surface.
>> Three repeater stations, 120 degrees apart in the correct orbit, could give television and microwave coverage to the entire planet. I'm afraid this isn't going to be of the slightest use to our post-war planners.
His short story The Sentinel, the precursor to 2001 A Space Odyssey, also has, IIRC, a description of the crew of a lunar rover frying sausages on a hob during one of their missions. And The Deep Range posits mass farming of whales to feed one eighth of the world population. I loved his fiction as a kid but the predictions haven't aged well.
In a public setting there should also be things like a panic / duress button. A simple lock (that only local security can bypass). Maybe an internal phone line of some sort. Possibly a wired connection to the net DMZ.
I hesitate to add a timer, because _sometimes_ people have real travel troubles while at the airport and need an extended duration to take care of that. Such nuances might not fit within the context of E.G. a 20 min max timer.
Alastair Reynolds is a modern master of this, in my opinion, with a lot of interconnected far-future “stuff” that still basically hangs together.
Clearly, this helps make works of sci Fi/speculative fiction/cyberpunk and related genres relevant far into the future.
If you try to extrapolate current tech 50 years into the future, you'll probably get it wrong and people reading your books during the time it's set in will think it quaint.
When you have to invent new future tech, it still feels mysterious and interesting.