Yeah it's easy to see writing in dynamic languages with optional typing and static analysis tools (e.g. JS with TS/Flow, PHP with phpstan or psalm), the type an

Yeah it's easy to see writing in dynamic languages with optional typing and static analysis tools (e.g. JS with TS/Flow, PHP with phpstan or psalm), the type analysis finds all kinds of different and subtle problems that unit tests probably wouldn't catch. Large integration tests often would, but are even harder to write exhaustive cases for. Types just make everything easier to do right the first time.