Some things are common within a culture, but even in places where most people are inclined to help their aging parents, like various countries in Asia, there are still children who reasonably choose not to do so. Cultural tendencies are simply that, tendencies. If your country doesn’t have a law requiring you to provide support, it’s because lawmakers know that in some situations it might be reasonable not to do so.
Did you notice how you wrote that you would be seen as downright evil, but you didn’t say by who? I feel like that’s something you ought to consider more carefully.
You gave an example of sending your father money, but you haven’t seen him for 17 years. This raises many more questions. Does he need your money? Is your money helping? If you found out that he didn’t need your money and it’s not helping, would you stop sending it? Are you sending the money to make yourself feel good, even though it’s not helping him? How do you think he would feel if you found out you were sending him money even though you’re jobless?
Finally, you used the word “unnatural” knowing that it’s just not true. That was certainly an antagonistic approach to the issue. Is that what you intended? Was it accidental? If it was accidental, what word did you actually mean instead?
People often make bad judgments based on incomplete information. As you know, it’s a sad fact that some parents do horrible things to their children. If those children leave, never come back, and never send money, good.