I would imagine that very mall projects have don't have well defined standards or have limited time (volunteers).
Maybe these are weak reason, but I don't know.
There was an earlier situation where we also skipped code review because the coders were all hotheaded cowboys who worked 5 PM to 5 AM, and this was the kind of thing that would just add tension. Also not necessarily a good idea, but we had a high enough political cost trying to implement a daily stand up.