Villains Should Pay Child Support

In my personal opinion, all villains who are the hero's father, should pay child support.  Even if they don't know they have children, they should give back payment as soon as their children are known.  And don't tell me they can't pay.  Darth Vader is the Second-in-Command of the Galactic Empire.  It's an empire.  It stretches across the galaxy.  He's the second-in-command.  They have money.  Why didn't he give Luke 18 years worth of child support after he realized their relation?  Sure Luke was older, on his own, was fighting Vader, and had been hidden specifically from Vader for his entire life, but that's not a good reason!  And all he spent it on was two giant spaceships that were quickly destroyed - one never even finished being built - that practically bankrupted the Imperial Government.  Honestly, how was that more important than being a good father?