Most of what we do is just data input and data display. And most of that is text. There aren't really any calculations or anything, beyond some simple sizing of UI stuff.

For database stuff, an ORM with some validation rules is generally enough, and couldn't be replaced with static typing anyhow.

For anything that absolutely has to be a certain kind of data, there are things built into dynamic languages to check the type of something, and you just call it as needed on a case-by-case basis.