Why do trees seem to resist more to tsunamis than houses?

Trees have a very small surface compared to walls, thus they oppose very little resistance to rushing waters and can survive a tsunami better than houses. However, a very strong tsunami will sweep aside trees and houses alike.

Mangroves, which are very special tropical ecosystems composed of numerous thin trees growing in coastal areas, do not really protect infrastructures and people onshore; they may dissipate the wave energy, but ultimately they will not stop a large tsunami.