Actually, I've seen it happen several times - including twice to me
It generally happens in three cases:
1. The Job is a 'starter position' - which means the hiring manager may not care too much - This is the easiest way to switch careers.
2. The Job is hard to fill - for instance when it requires re-location to an unattractive location.
3. Occasionally, the hiring manager is inexperienced or indifferent. When this happens in senior positions I usually become wary of the way the organization is being run.
Almo