Many times planes take off late because a passenger is late, or otherwise disrupts normal take-off.
While it's theoretically possible for the plan to leave without them, it's usually not done because it's required to remove their luggage from the plane.
Assuming this is a significant issue (a delayed flight can cause other delays to other flights, make passengers miss connecting flights, etc.) why isn't the luggage stored in a way that it's easy to find?
It’s all Murphy’s fault!* That guy makes every important thing become the last one to be found!
Apart from that If there are 400 passengers on a flight which has limited storage available there can’t be racks with 400+ bags stacked neatly in different columns and rows.
Those bags are on top of each other in tightly packed containers. So even though a computer will tell you which container to access, it won’t somehow bring that container to the front or unpack it. That’s what takes time and there is no great escape from that with what we have today.
And that’s the best case scenario. Talk about the cases where there are no storage containers!
On the famous TV Series called Dubai International Airport, I remember seeing them hold off loading bags for some passengers who had not boarded the aircraft in the time allocated. In such cases they would keep the bags ready to load and keep the staff on standby but they would not actually load the bags in anticipation that the passenger might not make it in time. Atleast on TV that seemed to help them at times.
You will always find something in the last place you look.
If your looking for more than one thing, you'll find the most important one last.
Source: murphys-laws.com (Just for a bit of a laugh. To be accurate Murphy just wrote one rule and people have been associating all the things-going-wrong rules with him ever since)
In addition to Hanky Panky's answer, one needs to point out that the process is not just taking the bag out. It also involves getting the appropriate gear (and personnel) back to the plane to actually be able to unload the luggage.
Also, if using containers, then you can't just get directly to any container, there's a single door through which containers are loaded/unloaded for each cargo bay, so if the bag is in the container that was loaded first, you need to unload all containers to get to it, then find the bag, and load back all the containers.
And I'm not really sure there are (always) procedures in place to know in which container the bag actually is.
Even if they get to the right container, they then need to go through all the bags in that container by checking tags one by one.
Not sure how they do things when not using containers, though. I'd hate to think they would have to unload all luggage piece by piece (checking tags along the way) until they get to the right bag...
Luggage storage isn't optimized for fast retrieval of individual items, because instead it's optimized for:
There are probably some other constraints as well, related to weight distribution and connecting flights.
A library is (ideally) optimized for fast retrieval of individual items. I can fill the same space with a lot more books and do so much faster than a properly sorted library can - albeit there do exist ways for libraries to make the difference less extreme.
If luggage was instead stored for easy retrieval of individual items, one would presumably have to sacrifice a combination of:
