Although waste bunkers are not considered hazards under the rules, they certainly can be hazardous to golfers' scores. They are not common in golf course architecture, but aren't exactly rare, either. Sometimes they run alongside a fairway, and when waste bunkers do appear on courses they are sometimes in positions where they come into play with regularity on errant shots.
As noted, when a course has waste bunkers it might also have local rules governing those waste bunkers. So if you are playing a course where you know they exist, it's a good idea to clarify their status before beginning play.