Flamestrike
Legend
The PHB states that "Lawful good (LG) creatures can be counted on to do the right thing as expected by society. Gold dragons, paladins, and most dwarves are lawful good." in the alignment section. So a LG character wouldn't necessarily have a moral struggle, depending on what society expects of him.
You're ignoring the qualifier of 'do the right thing' when it comes to conforming with societal expectations in the above quote.
If society expects a LG creature to do the wrong thing, he wont do it.
'Right' is defined as: 1 : righteous, upright. 2 : being in accordance with what is just, good, or proper conduct.

Definition of RIGHT
righteous, upright; being in accordance with what is just, good, or proper; conforming to facts or truth : correct… See the full definition
I'm struggling to see how lobbing a warhammer at the legs of a starving street urchin who just stole a loaf of bread is 'the right thing to do', or how it could be considered 'proper, good or just conduct' or how in a morally good society, such a thing could be tolerated or even expected of people.
Lawful neutral (LN) are (RAW) individuals whom act in accordance with law, tradition, or personal codes. Clearly @Oofta's PC had a strong personal code about 'upholding the law' and 'all crimes must be punished'. That's not a morally Good code at all, so to me he sounds like a LN PC.