After some serious testing, I don't think it's that bad actually.
The reason it threw me off is because Plastic consumes INSANE amounts of Petroleum Gas, compared to Coal. So it looks like you need many more drones to transfer fluid.
But once I started expanding further and setting up smelters and stuff, I noticed that even large amounts of solids require lots of drones. The reason it seems weird is just because Plastic is the first fluid you set up, and it's very skewed.
After this, I think the numbers are fairly balanced.