My kind of silly personal headcanon as to why Wolf/Fox never actually catch Rabbit and seem to have an almost jokey and sometimes even friendly relationship with him is that the society they're in is structured where they're like proud of their wild animal heritage, but, they obviously mostly live a pretty domestic lifestyle where they have policing and have predators/prey living together pretty amicably.
So I like to think that as part of their like respect for each individual species and also just out of necessity for their mental/physical wellbeing, despite not actually killing and eating eachother anymore, the animals all do engage in like essentially play hunting scenarios as part of like enrichment and social norm.
I also think the whole like having respect for different species and their proud heritage or whatever is why things like Fox, Wolf, Rabbit & Terrapin are used in place of their actual names, I think it's like polite and a mark of respect in their society to address adult animals by their species name and to only use their actual name if you have a closer relationship or I suppose need to differentiate between same species animals lol.
Anyway, this is my headcanon that I use if I want to think about the show in a more "realistic" way and with scenarios where the predator/prey animals can be friends etc, I also think it gels pretty well with the way the general comedy in the show around the hunting tends to be done.
The only canonical things which really negate this are when Fox is eating that leg of what is pretty heavily implied to be the sheep that was sat next to him, Lucy's mum getting eaten by that wolf lol and also when the schools teacher disappears and everyone looks at Fox. I feel like both the Fox ones are pretty easy to ignore and just be like "Oh no the sheep was in the bathroom and that was just donated or lab grown meat " (& I'd say it's probably still pretty rude to eat meat in front of prey but Fox doesn't GAF lol) and like the teacher one could just be a joke or Fox has trapped her or something but in accordance with animal law not killed her. Lucy's mum is definitely the one that trashes my headcanon most but I wouldn't put it past Rabbit to just lie about something like that lol and also, through headcanon anything is possible 🙏🏻
Anyway that's my weirdly hyper specific headcanon about why Wolf & Fox suck at hunting so much and also never seem to go to jail for it, if anyone wants to use it to make them friends with Rabbit (or god forbid for Rabbit/Fox) then please be my guest