I probably would not notice if someone connected to my home network wifi for a short time.
Anyone doing this would need to be close, and if outside would likely be visible. A technically competent neighbour might manage but the benefit to them might not be that great particularly as they might have their own broadband anyway. A business network might be more interesting.
As far as crime is concerned I do get regular phishing emails.
That's exactly it. I have no interest in cracking my neighbours wifi in a usual circumstance as it's almost certainly not as good as mine anyway. At best it's the same (if they have opted for 350m) and even then I'll probably struggle to hit those speeds over Wifi rather than cable.
I would do it in the event of some sort of outage, assuming only my house was affected, but I wouldn't do any harm, and wouldn't saturate the connection - then they might notice and boot me off.
To be honest, if a neighbour got into mine I would likely notice eventually because of the Unifi controller which gives me lots of data, but I wouldn't really care. If a neighbour had issues with their internet I'd happily let them use mine.
I actually have a guest network set up with a payment portal on the off chance anyone wants to give me money, but nobody ever has!