We have the interior model automatic door with the light sensor probe on a cable. The door is mounted on the inside and the probe goes through a small hole in the wall. We adjusted the sensitivity of the sensor by turning a screw, when we first got it, so that it would open and close at a time that was good for our chickens. We haven't had a problem with chickens being left out. We've had it for about 3 years.
When we first started using it, we made sure it was opening every morning and closing every night. We also made sure that the timing was good and that nobody was being left out. I think it's good to do this with any automatic door the first week, just to make sure it's working as intended.
You can also add a timer to the light sensor model or just get a timer model. We didn't want to hassle with changing the timer as the day length changed, that's why we bought one with the light sensor. If you want a timer model, there are several different manufacturers selling them. You can even make one. There are lots of different threads on automatic doors on the forum, including how to make them. If you want a light sensor model, we have the one that Foy's and Wells Poultry carry. Although Wells is in the UK, we received our order as fast or faster than items we've ordered from the US. It's battery operated.
I think most people that go away have someone taking care of their chickens. Some have automatic doors. Some people leave their chickens in the coop or leave the door to the run open. It just depends on your set-up. Not everyone has enough room in their coop or a secure enough run, to leave them unattended.
I've noticed that people with livestock take trips a lot less often than people with pets. Like, sometimes never!
(I want a pet nanny, too!)