Can you help me assign the logical fallacy

I would apprentice help pinpointing the logical fallacy

A: says action can be committed by accident or incompetence 

B: compares to a crime and states extreme or uses laws as justification to be harsh to incompetence while as it seems, after all that dehumanizing the incompetent in question   

the B in question said this (If you accidentally fire a gun and shoot someone you're still going to jail, X never had rights to begin with so we shouldn't cater to them)

“Even a dog knows the difference between being kicked and being stumbled over.”― Oliver Wendell Holmes. Courts are supposed to take such differences into consideration, but it depends upon the individual judge.

I'm not sure there's a logical fallacy here, but I don't fully understand the argument that's being put forth.

Statement A seems true ... among the things that can lead to a particular action, things happening by accident or because of lack of skill or knowledge ... along with other possibilities.  So, Statement A seems true.

There seems to be a non sequitur between A: and B:.  There's nothing in B's statement to explain how the possibility of doing something by accident or incompetence links to crime.  I don't see how doing something either by accident or through incompetence is in any way connected to justifying harsh laws or what it is about that comparison with crime dehumanizes incompetent individuals.  To form a solid argument, those missing links need to be provided.  

The final statement seems to do a bit of cherry picking in that it's correct, someone who shoots someone accidentally is likely going to receive some sort of punishment; however, it's unlikely that the punishment would be the same as that meted out to a serial killer who shoots her or his victims intentionally.  If I understand correctly the intent of the discussion, the point of the last statement is more that there's still some sort of punishment, not that all such punishments are identical and the statement doesn't focus on the differences that would probably be in play.

The absence of a structured argument makes it difficult to identify the point of the discussion, whether there were two different points of view, or flaws or fallacies.

To know whether a fallacy is here, we need to determine the premises and conclusion.

A offers a single premise, 'Action can be committed by accident or incompetence' (this is arguably unsound as an action can also be committed with malice)

B goes through a process of comparison and arrives at a conclusion - I think it can be paraphrased as, 'A person that commits an act that causes harm accidently or incompetently should be punished.'

B's process of comparison must have indicated a second premise to them - something like, 'People are punished when they cause harm by accident or incompetence.'

This would give us,

Premise 1: Action can be committed by accident or incompetence
Premise 2: People are punished when they cause harm by accident or incompetence
Conclusion: A person that commits an act that causes harm accidently or incompetently should be punished

The difficulty with knowing whether there is a fallacy is the lack of clarity with regard to whether the statements are Type A logical forms (all, every) or Type I logical forms (some).

Consider the different inferences that flow from these examples,

Premise 1: All actions can only be committed by accident or incompetence
Premise 2: All people are always punished when they cause harm by accident or incompetence

Premise 1: Some actions can sometimes be committed by accident or incompetence
Premise 2: Some people are sometimes punished when they cause harm by accident or incompetence

It is also worth considering A's use of the word 'can' (a modal verb of capability) and B's use of the word 'are' (the verb to be used to express existence of a state of affairs).

A modal verb of capability implies a Type I logical form unless it is qualified (e.g. with 'always')
An expression of existence implies a Type A logical form unless it is qualified (e.g. with 'sometimes')

If we follow this convention then the premises would be something like,

Premise 1: [some] actions can [sometimes] be committed by accident or incompetence
Premise 2: [all] people are [always] punished when they cause harm by accident or incompetence

We can now turn our attention to the introduction of the word 'should' into the conclusion.

'Should' is a modal verb of moral necessity (in this context).

The following argument would be valid,

Premise 1: [some] actions can [sometimes] be committed by accident or incompetence
Premise 2: [all] people are [always] punished when they cause harm by accident or incompetence
Conclusion: A person that commits an act that causes harm accidently or incompetently is punished

But - It does not follow from premise 2 (people are punished) that people should be punished.

This would be a form of naturalistic fallacy 

This is what I understood: 

Person A does something wrong by accident or incompetence. Person B compares what A did with what C did, and C's action was horrible. Therefore, A is a horrible person.

We could come up with examples and pinpoint the fallacies.

Example:

Peter ran a red light but he thought he had more time. John says that Mary also ran a right light but she ran over someone. This is super irresponsible and Peter should be viewed as a super irresponsible person that doesn't care about innocent lives.

This would be ad hominem (guilt by association) because Peter's action is associated with the actions  of all super irresponsible people.

This thinking might also strip away context. For example, suppose that Peter knew that if he made the stop, the car behind him was so close that they would've crashed. But the streets looked kind of empty with no visible pedestrians and he thought he had enough time anyways. Mary, on the other hand, saw that the light was already red, the street was busy, and there were a lot of pedestrians. 

The fallacy I can think of for the above example is appeal to extremes. We could frame the claim like this:

A claims: Peter ran  a red light but he just made a mistake.

B claims: If we treat crimes as "mistakes," soon enough we will have people like Mary just committing "mistakes."

B takes A's argument to the extreme to make it sound incoherent by using the slippery slope fallacy. 

Notes: I kinda want to convince myself on the use of the appeal to extremes fallacy. 

X is a mistake.

If X is a mistake then Y is also a mistake.

X = Peter runs a red light.

Y = Mary runs a red light.

Y is the extreme of X because of how they occurred.