even "holywood" physics are based off "real world" physics
for example, in "holywood" physics if a door is blown off a car it will very unlikely end up standing on its edge (poor example of physx attempt), it may fly further than you would generally expect but its movement, bouncing, spinning, etc would be what you would expect from something that size, shape, weight traveling at that speed, trajectory
change the weight, speeds, shapes, trajectory and the resulting movements should be what is expected as a result of those changes
just from that it sounds complex, but thats nothing compared to the number of calculations required for that sort of movement to take place, especially considering the fact that where the main force impacts that hits it, what part of it hits the ground and bounces, and resulting aerodynamics are all variable and will impact the number and complexity of the calculations that are taking place
going back to your real world example, the physics involved in those situations is fairly immense. a bullet has an arching trajectory, currently as far as i know there are no games that take this into account, bullets just fly straight, i would find this alone very interesting and would make games much more enjoyable as, as in real situations, you would have to take into account wind speed and distance for long distance shots
also how bodies react when collisions occur would be another real world example, in the real world you may not be watching and going "wow that looks so realistic and cool" but in a game it would be just another thing that, when paying attention, would hold the players attention and captivate them
all these "real world" physics examples are the base of "holywood" physics, drop the weight of an item and suddenly it flies twice as far, explosions blow bodies higher into the air and over greater distance, all while running the same set of physics calculations causing the actors to react as you would expect
the idea is to make things happen as you would expect them to happen, not for items to react unnaturally, if its unnatural then generally it sticks out like a sore thumb, if its natural then you wont notice it as much, you will see it, it will do what you expect, and you will be satisfied and forget about it, unless youre paying attention and watching what it does to make sure it does what it should. whether you realise it or not your mind is doing a huge amount of physics calculations itself while watching these games, which is why bad physics is so obvious, your mind calculates one rough outcome, something completely different occurs and its like an error pops up in your mind
one prime example i would say would be the collision calculations in oblivion, whenever you run into an object thats moveable it reacts in an extreme manner, like fly across the room and slam into the wall at a force that makes it bounce about 10 feet back from the wall, even one time a piece of wood spun around on one end for about half a minute before falling over! you notice it because its not what you would expect to happen, you laugh because it looks funny, but in the end its a loss for the physics engine (or the values going into it) because there is an incorrect calculation going on thats causing unnatural effects
i suppose to concisely sum up this rant id say that this should give you some idea why physics is so costly (atleast resource wise!) to implement and how when properly implemented the results are not stunning unless youre paying a lot of attention to what is going on, otherwise it will just be what you expect and nothing out of the ordinary
--edit--
silly spelling mistakes
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