How do I tell my parents they are being rude to my husband and BIL?

On my parents birthdays (mine and my husbands) we send both of them a card with $50. On my birthday they send me $20 and a card, but they don't send my husband anything. Not even a phone call! They do the same thing to my sister and her husband. I don't think it's right. My husband works for our money, and yet he is left out when his birthday comes around. It's not that they don't know, either.. I always drop hints about his birthday coming up. What do I tell them? I think I'm going to say that if they are going to forget my husband, then they should forget me, too.