Just got 2.7% for my title bump. Hurray.
Sometimes specific title requirements preclude this (e.g. "We don't give new people X title immediately"), but it's a good rule of thumb.
It makes yearly pay bumps much easier for your manager to justify ("So-and-so is well within salary ranges for their title"), versus them having to fight for an exception to policy.
People would find out about this and would leave resenting that they are underpaid.
Your hiring manager usually doesn't care, as long as there aren't any req:title limitation issues, because it attracts you and generates less paperwork on their side.