Wow, I work in a big, non-software-focused, multinational company, in a mechanical engineer role. Your post describes our exact review process.
What more, it seems managers always set the expectation high, or vague, that way everyone always get 3/5 (meets expectations). By now I'm almost 100% convinced that there is an official HR guideline that they are not allowed to give higher than 3/5 overall rating.