That might be true for first time offenders but what about repeat offenders? They can't be said to not be familiar with the possible judicial consequences of their actions.
That's possibly a third category to add to "spur of the moment crime" and "I don't think I'll get caught": "I don't care what happens to me". A lot of crime done out of desperation, by people with nothing to lose, is precisely that: they are so desperate they don't value their life or the lives of others [1]. In that case, prison and even the death penalty is a poor deterrent; if you expect to live hard and die young, what can they threaten you with anyway?
[1] A journalism/essay book from my country (not the US), depicting the lives of youngsters in shanty towns, interviewed many of them. A surprising number of them claimed they didn't expect to live past 30, and didn't make any plans because plans were meaningless to them. If they died for whatever reason, "so be it". (By the way, in my mind this isn't an indictment of these people, but rather of the society which makes them believe they have no choice and no future).
That's a nice idealized model of human decision-making except for that it's not even approximately how people actually make decisions.