Are different pasta shapes easier/harder for factory machines to make?

It's likely the handling and packing that's responsible for the higher price.

Among all the common dry pasta shapes typically sold in the grocery stores, lasagna sheets seem to be the most fragile.

Unlike many dry pastas that are kept relatively compact in plastic bags, dry lasagna sheets needs to be kept in like-shaped boxes to minimize breakage, and even then, a few sheets may get cracked from shaking around.

I'm not entirely sure if this is the main reason, but that's how I reason with it.

Yes, some shapes require more sophisticated equipment to make, and as a result those will be priced higher. Cavatappi, troife, busiate, fregola de sardo, and any kind of filled dried pasta are examples of this. Some can't really be extruded at all, some need to be extrduded slower/more carefully, and others require post-extrusion processing.

Other shapes are not actually harder to extrude or dry, but are simply obscure, and as a result are only made/imported from companies who make pasta in smaller batches, and thus price higher. Generally, this small-batch pasta is also made with better processes (bronze dies and slow drying) that makes it more expensive to produce as well. Examples of this would include casarecci, gigli, and bucatini.

Finally (per Anastasia's answer), some pastas are packed in such a way that makes them more expensive to pack, ship, and handle, which is then reflected in the sale price. This would include your lasagna noodles, as well as conchiglioni (big shells), vesuvio, and fettuccine sold in "nests".

It might be simpler to say that only "mainstream" pasta shapes that can be made quickly and cheaply and easily and tightly packed are cheap. Everything else is more expensive.