More like bad requirements. The system knew how many dinosaurs of each species had been released into the park, and the inventory system was only supposed to figure out if any were missing. No sense in looking further than that, after all where should the additional dinosaurs come from.

That was the main theme of the book. Everything was well designed with failsafes, but too many of the design assumptions turned out to be wrong. Expecting only the expected lead to many small mistakes that were harmless individually but together snowball into a disaster.