It only appears the holodeck needs scant details because we (the viewers) are not privy to the configuration time that needs to be set up for any holo-programs to be run. All of that setup time is almost always done off-camera. We usually get to see only the initialization of the program.
While the holodeck holds a significant amount of general information within its database, it also has access to the main ship's or starbase computer's databases of information, personnel files, psychological profiles, all personalized configurations and settings have to be applied before the client enters.
When the holodeck is emulating a physical environment or technology, all information for that technology must be included for an accurate simulation. When the Enterprise was caught in an energy draining device (TNG: Booby Trap) Commander LaForge created the holographic representation of Dr. Leah Brahms using her personality profiles to help them escape the trap.
Creating material for the holodeck is both a science and an art and is likely one of the occupations of the 24th century that does not suffer from a lack of people wanting to develop for it. The holodeck is one of the most sophisticated technologies of the Federation requiring knowledge of psychology, physics, matter replication, auditory and sensory sciences as well as an artistic flair for seeing the world at large, both past and present.
We tend to walk in on someone running a program, for example Tom Paris' bar in New Orleans, where he has meticulously programmed in the psychological profiles, perhaps based off of either real people or character archetypes saved in the holodeck matrix database.
The physical parameters of the bar are either drawn from actual plans of the locations, which wouldn't be too hard to do given 23rd century technology, or from photography extruded into a 3D environment and then given simulated weight, colors and textures.
Creating holodeck simulations like Tom Paris and Harry Kim's Adventures of Captain Proton or Katheryn Janeway's Leonardo DaVinci's workspace require more development but since one is a holonovel and the other a famous person, were probably developed before they arrived on Voyager and were tweaked and personalized.