All too often, code review amounts to no more than making sure there are no grievous mistakes. Management only cares about you completing your own work, and if reviewing the work of others slows you down, that's your problem. Time spent on code reviews have never counted toward mine or anyone else's performance. A bad PR making it to production certainly gets negative attention, so that's the aspect given priority. The incentives do not align to make code review a place for knowledge transfer.