Why are we building on floodplains?

And who’s responsible for the building?

photo from current NSW Sydney floods showing floodwaters surrounding a house roof, treetops, and the railing of a bridge
The new Windsor Bridge over the Hawkesbury River, Sydney, on 4 July 2022. This is the third time the bridge has been flooded since its opening in May 2020. Credit: Jenny Evans / Stringer