As we get further into this arc I can only come to the thought that this author has very limited character archetypes and personalities. "Oops all wizards" arc really highlights this issue with all the wizards are nearly the same kind of wizard.
The Panama canal would have been wrecked by the passage of time as it is not just a trench dug between the two oceans. It relies on a lot of moving parts to facilitate travel of boats and would need a lot of staff even if there where still computers and power to run the locks.
That said I am...
Husbando is doing this so that he can still have his hot wife to play around with. Note the language he used about if Mr Owl found out how many licks it takes to get the the center of the scum pop here it would make things difficult.