Regarding your first paragraph, rarely are the gate agents telling the public the entire story. The truth is typically more complex and basically not of concern to the average passenger.

As for your conclusion, it's just not accurate. Systems _are_ used for scheduling and allocation of equipment and crew resources. You just have to realize that getting you, as an individual, to your destination on time on any given day isn't the number one priority of the company. There are a lot more concerns they are considering. If the airline industry is really as dysfunctional as you think, with such shortcomings in areas as important as equipment and crew scheduling and allocation, you should drop whatever you're doing and start an airline. You'll soon be filthy rich and do the world a great service.