Simply put, the Consumer Product Safety Inspection Act (CPSIA) says that all products made for children 12 and under must be put through extensive and expensive testing...making it impossible for most, if not all, small businesses and crafters to sell anything.
So if I wanted to sell you a doll, or a dress, I couldn't. Because I couldn't afford it.
If you wanted to buy a vintage storybook, you couldn't. Because the antique shop can't afford to test it.
If you like giving unique kid gifts, too bad. You couldn't afford them even if you found one.
The best thing you can do if this bugs you is to learn about it and then spread the word.
Sarah Jane Studios has the most informative post, in simple language, I've read. She has all the links you need to educate yourself on this, and she explains exactly what you can do.
Download the Etsy Action Kit.
Email your Senator.