We use "of" instead of "for" in some kinds of sentences because the adjective which is near infinitive describes the character (evaluation) of the person. For example
It was careless of you to leave your bag on the train.
but I don't understand why we use "of". Is that related to the features of prepositions?
It was careless of you to leave your bag on the train.
It was careless for you to leave your bag on the train.
There's not a big difference between these two sentences. Honestly, it's probably just easiest to consider "careless of you" a well known phrase, I believe it is more likely to be used than "careless for you" for that reason alone.
Of X is used to express possession (among other unrelated things). The logic that is happening in the first sentence is that a quality is being considered as belonging to someone, to express that they are associated with that quality temporarily. In a sense, it is being said that "carelessness belongs to you" though explicitly saying that will sound weird. But it's OK to say "careless of you." (and your carelessness also would work in other sentences).
For X is can be (from Google) "used as a function word to indicate the object or recipient of a perception, desire, or activity". That's the logic that's occurring in the second sentence, "you" are receiving carelessness (which you caused) and "to leave your bag on the train" is another thing that is careless.
You could just say "It was careless to leave your bag on the train" and the for you can be implied by the your in the phrase, though this would also be appropriate if someone else other than you left it, so there is some possibility for ambiguity.
So both of these are valid and use alternate paths of logic to arrive at the same conclusion. I would bet the first one is more idiomatic.
There is a big difference in structure, though the meaning might not be so different.
"Of" can be used with most adjectives that describe a quality of a person in this way, with or without a complement:
That was kind of you.
It was brave of her [to stand up to them].
It was foolish of me [to even try].
But most adjectives do not take an argument with "for", and nor is the construction above available:
*It was brave for her.
(The * means this doesn't occur).
So the construction with "for" is different. It uses a purpose clause:
It was brave [for her to stand up to them].
You can see that this is a different construction by making it the subject:
For her to stand up to them was brave.
but not
*Of her to stand up to them was brave.
because "of her to stand up to them" is not a constituent of the sentence.
On the other hand
To stand up to them was brave of her.
works fine.
Note: I've realised that you can have "brave [for her]" as a constituent, but with a different meaning:
To stand up to them was brave for her.
means something like "by the standards of bravery I expect for her, this was particularly brave", whereas with "of" it does not carry that added meaning. This is easier to see with "kind":
To give away her lunch was kind of her.
is neutral, saying she was being kind; but
To give away her lunch was kind for her.
implies that the speaker doesn't expect that kind of kindness from her: there is an implied criticism of her.
This meaning is possible in the original order, ie.
It was kind for her to give away her lunch.
could have this reading, but it is ambiguous with the "[for her to give away her lunch" reading, and I think the latter is the more likely interpretation.
It is a very big difference. Why? What does this sentence mean? Sarah is a friend of mine? That she is my friend. And how about that? Sarah is a very good friend for me. of means that something comes from a person or it belongs to a person. Your example shows that some "you" left his bag on the train. It came from him, it was his fault, no other person. for totally is not correct in this case. Maybe when you said I was very careless to you, that I left your bag on the train it would be correct.
I hope that I've helped :)
