One company I was with had a rule that former employees couldn't be re-hired for 18 months after they left. This was to stop employees getting pay rises by via the hiring process rather than the standard review process.

At another we had somebody from the helpdesk join our team, he rapidly skilled up but the company had a rule that max pay-rise was 20% annually and he was on half what everyone else was on. Problem was escalated until an exception was approved by senior manager and he got a big 1-off payrise.