That's called a destination control system, and it works that way because of the massive efficiency gains of letting the elevators work out who should go where.
We had those in the Centre Point tower, where I used to work. They were awful. As you swiped through the security barrier you'd be assigned a lift. However, if you missed the number or the barriers broke (which they often did) there was a good chance of getting in the wrong one.
There was a public restaurant on the top floor, so the lifts frequently contained panicky people riding up and down until they eventually got to the ground floor.
Also the lift systems occasionally crashed mid-journey. The lift would stop, the lights would go out and the LCD screen would blank and run through a boot sequence before everything came back up.
Sounds like you had a really beta version? The ones I've used (n=2) worked fine, and the lift assignments were done just outside the elevator, where you'd usually have the up/down buttons. As the elevators arrived, little screens on the outside showed the floors they would be stopping at.
These were private office buildings though, I can definitely see the public restaurant causing havoc with its endless stream of noobs...
I think they're just really old - I have a vague memory of seeing an engineer armed with a 5 1/2" floppy disk. They definitely didn't do anything as fancy as showing which floors they would be stopping at.
The building's now been turned into posh flats - there's no way I'd consider living there (apart from being almost infinitely out of my price range) without being sure they'd been replaced.
What's with this? You have floor you're on and a floor you want to go to. If some else presses a button before the lift passes, pick them up too. Awfully conventional, but everyone understands it.
Until you're in one of those office buildings where everybody has lunch at exactly 12, meaning first you wait an eon to find an elevator where you can squeeze in, and then you ding-ding-ding-ding your way slowly down to the ground floor, stopping at every floor to show people that this one's also full!
Couldn't you just use a weight sensor to determine whether an elevator cab is over x% of its rated capacity, and make that one ineligible to respond to external calls until after some people exit?
That wouldn't require changes to the user interface, and the doors would only open if someone can actually get on.
That, plus an assumption that most trips are between the ground/garage floors and one of the higher, occupied floors should be sufficient to reduce congestion without requiring someone to push a floor button before entering the cab. Adding a clock to the elevator controller would also help, such as by stationing empty cabs at the exit floors in the mornings, and distributing them among the occupied floors in the evenings.
I can think of a lot of ways to improve elevator scheduling without changing the user interface, and even if I did change that, I could certainly provide some mechanism to select a specific floor without installing a touchscreen GUI. Wave your employee access RFID badge at the button panel to pick the floor where your cubicle is, for instance.
Its a havoc when there is a crowd, like the floor housing the common cafeteria/lunch place in an office building. In a group of people waiting, inadvertently someone misses out to specify their floor and panics!
Also, surprisingly large no. of people make a mistake in selecting the floor they need to go to (visitors, new joinees...)
Efficiency gains are a big deal, too. Consider that even being able to get away with one fewer elevator saves space on every floor of the building. The taller the building, the more valuable it is.
