If you put 20 lily pads in a hopper and take a comparator output, the signal will travel for two blocks. But in case of chicken eggs, you only need six of them to get a signal of this strength.

Summary
It takes 20 lily pads to get two-block signal strength, but six eggs to get the same strength. Both items stack up to 16, shouldn't they give out signal of the same strength with the same amount of items, say, six?