User blog comment:Gardimuer/BioShock Infinite Demo & Screenshots/@comment-3042051-20100924025352/@comment-1401334-20100924190025

Usually in games if some action is supposed to destroy the environment they just use a decal. I.E: You melee a piece of glass or shoot a wall, and (if it doesn't break) it just gets a new overlay texture to look like it has holes or cracks in it.

They would probably include changes to the environment if it was the result of a scripted event, but if they included permanent changes for every player action it would be way too much information to store and would cause the game to lag.