The problem now is that it's the producer that decides what the packaging is, but it's the consumer (or the state) who pays for the collection and recycling. By making the producer pay for it, you give them an incentive to make it more efficient.
Once the consumer has paid, it's your money now. The incentive is clear, less packaging means more money you keep. That only big producers will actually see the per-ton payments as significant instead of just having to pay absurd registration fees is a separate issue.