How come the WG have invented superhuman robots that can fire lasers from their mouths, but haven't invented a plane yet?
They totally do though. An old guy did it with his automatons.Pacifistas are cyborgs, not robots created out of nothingness. I think it was already stated in this manga that they don't possess enough technology to create a robot out of nothing(iirc) but they could create cyborgs which are based on a human. Besides, we're in a pirate manga. It's just that Oda probably thought the usage of ships was more illustrative/representative of the type of mangas he was in.
Also, according to Sentomaru, the funds required for the construction of just one Pacifista are roughly equal to that of a Marine-issued battleship, so it seems to require a great amount of money. Maybe they don't have the necessary money to try to create a machine they are unable to make conceptual plans about
Go home and dieOne piece ****ing blows since the end of the fishmen arc