I ran into a grammar book that claims this sentence as incorrect:
Every year, more tourists travel to Disney World than the Louvre
They are saying it needs to be "...to the Louvre".
Other sources say that second preposition is optional when saying something like
Martha was praised not only for her technique but also (for) her costume.
The only way the first book is correct is if contrasting comparisons are treated differently than comparisons noting a similarity.
Would appreciate any clarifications on who's right?