There is a certain amount of that going on. After Hurricane Hazel in Toronto, the government did buy up a lot of land on the Humber and Don rivers where houses

There is a certain amount of that going on. After Hurricane Hazel in Toronto, the government did buy up a lot of land on the Humber and Don rivers where houses were swept away, they are now parkland. the trouble is, moving people out of a flood plain within a city is easier than moving an entire city that is a substantial economic entity in its own right. So I think you're right that where practical, people shouldn't live in flood plains, and perhaps they shouldn't even have a choice in the matter.