For everyone that wonders why the achievements may not unlock:
We've been talking with Origin about the issue—there was a bug introduced to the client that was preventing some achievements from being unlocked. There's a patch that is apparently on the test client, but other players haven't had any luck with it. The update will be rolled out next week.
Mini Metro does store all achievements locally, so you haven't lost any progress! When the Origin bug is fixed, you'll be awarded the achievements on Origin retroactively the next time you start the game.