Making Merit - Is it really Meritorious?

Whether raised in Eastern or Western societies many people adhere to the concept of 'karma' - that doing good brings good things, bad brings bad - in some form or another. Every normal person wants to receive 'good', and so we see many people 'being good', with a double-sided motivation - they not only want to receive good, but they also fear that bad things will happen if they are not good. However, if a person is truly good, wouldn't they do good simply because they are a good person, not...