1. You build your project, and it fails in the places where API changed.
IDEs can even pinpoint those locations without building a project
2. You run tests and they fail if the behavior changed
Literally nowhere is "oh, do an automatic search/replace of imports" is a tool for fixing your project or figuring out necessary changes. Except in go, apparently.
Willingness to play russian roulette with major versions may work in small organizations. In large-scale, you can't risk subtle behavior change that still compiles. That's the source of many black magic debugging sessions.
IDEs can even pinpoint those locations without building a project
2. You run tests and they fail if the behavior changed
Literally nowhere is "oh, do an automatic search/replace of imports" is a tool for fixing your project or figuring out necessary changes. Except in go, apparently.