I don’t know if it’s “our culture”, it’s part of it but personality also comes into play.
If you spend time and effort doing something for someone and expect nothing in return it’s only natural that many people will feel uncomfortable unless they believe they understand why you’re doing it. It’s not necessarily transactional; understanding the motives of others is how people make sense of human interaction. Their understanding doesn’t have to be correct! It just has to make sense to them somehow.
Some possible reasons a person is doing a thing for me:
* They like me, we’re friends
* They like doing the thing or keeping busy
* They have a religion (Christianity, GNU/Linux)
* They like to feel helpful or useful, to teach or to demonstrate expertise
* We have a group bond (church, neighbourhood, club, etc)
* They’re doing me a favour. I’m a useful person and I’ll be able to do them a good turn in future.
* They owe me something (loyalty, money) and they’re paying me back by doing this
* They’re trying to rip me off somehow or get something out of me
* I’m incapable and they judge that I’m clearly in need of help (charity)
More self-reliant people are the ones who seem reluctant to accept free help. I think it actually hurts their pride a little to have to rely on you and not be able to give something in return. Accepting some jars of jam or a bit of money in return seems like a kindness.