ATRACTOR

Question: The models given for the tides seem to imply that the time of a high tide (or low tide) at a place depends on the longitude (since the time at which the moon "passes" over a place is related to the longitude of the place). How can it be explained that there are places with the same longitude and very close (distance of just over 20km) where the times of high tides (at both places) differ by several hours?