I think most boaters are very helpful, we aren't unusual, though word soon gets around if someone takes the piss. The tow path telegraph is very efficient and we will walk away if we see certain boats coming along.
In some ways it's like an old fashioned neighbourhood. People will knock and ask to borrow stuff, I've given out a length of tin foil, a cup of milk and a potato since we left the marina.
When we bought our first boat and were travelling from Crick to Reading we were given so much help and advice by experienced boaters. The least we can do is now help others, Steve was given knee pads someone who saw him kneeling on the tow path cleaning the boat and I was given a potato masher when I realised I didn't have one.
Boaters who travel a lot to new places don't know where the nearest shops are, so can run short of stuff. They also may not have a car though most do have a bike
When I lived in a house I always kept well stocked cupboards, I do the same on the boat so it's no hardship to share what we have or give someone a lift in the car.