"I suppose you're just the epitome of a good Samaritan in the right place at the right time."

And you will be in the right place, at the right time, at some time, then you can choose to act or ignore, I hope you can find it in you to act.

I think I am just normal, and you are avoiding getting involved because of fear, but I guess as none of that stuff happens to you then really you have no idea of what you would do?

The epileptic had an episode mid flight, after the request for a doctor or medical personnel raised no assistance I stepped into to assist a 20'ish flight attendant with no idea what to do, in case you are wondering, here's what you do.

"
It might be scary to witness, but do not panic.

If you're with someone having a seizure:

only move them if they're in danger, such as near a busy road or hot cooker
cushion their head if they're on the ground
loosen any tight clothing around their neck, such as a collar or tie, to aid breathing
turn them on to their side after their convulsions stop
stay with them and talk to them calmly until they recover
note the time the seizure starts and finishes
"

"If I found a minor without her parents then I would contact authorities"

Ok, so let's play a scenario, you are walking along the street alone, and you see a small child, of the age you'd normally expect to be accompanied. In your world you what? Phone the authorities, right, so in the 10 to 30 minutes that it might take to raise that help, what are you going to do, just walk off and think, well, I called the authorities and now it's not my problem, you just walk away leaving a child on their own?

The minor's I assisted were walking through a park late at night in their bedclothes, me and a partner contacted the authorities then hung around as it seemed odd, not long after some very grateful parents turned up, the children had simply decided to take a walk.

"I would do more harm than good, me, a stranger in a big city, putting my nose in where it doesn't belong"

Everyone is a stranger in a big city. That's the thing isn't it, now imagine if everyone felt like you, no one would get involved in anything that didn't directly benefit them and carried no risk. You are content to let the police, fire and ambulance services get involved, they are people too, do you think they don't fear injury or perhaps because you feel you pay them to do it, that makes it okay for them to take on risk and you to avoid it?

That is a sad state of affairs. Evil thrives when average people do nothing...

"My life is too short to get caught up in strangers' drama, because that will definitely shorten my life, and possibly also drain my pocketbook, place marks on my criminal record, or indeed put my own self at risk of injury"

You have no idea what tomorrow brings, how long or short your life will be, or if your actions today will set into motion an event that is bad, or good. You are worried about your pocket book, having a criminal record, injury, I understand that, now, can you tell me what you do with this life that is so worth distancing yourself from any risk? Would you make exceptions if you had family or friends who need help, or would that too be based on an initial risk assessment?

What if you helped a stranger who spotted a mole on the back of your head that looked odd, then you got it checked out and removed and that saved your life... I'm not saying that's likely, but your spin, that any involvement in society carries too much risk is perhaps forgetting how little of life we have control over...