Things are going to get really brutal for HR when $15 an hour hits. That will be the carrot that gets the interviewees in the door, so naturally they'll want to know if they'll be getting the great four-oh or close to that, because cashflow. HR can be honest with them and say "We can't guarantee full time hours and many weeks you should expect 20 or even 12, also here's a list of the 1,978,483 tasks we'll expect from you" and the interviewee will flee before they're done talking. Or HR can lie and say "Oh yeah sure we can totally give you hours every week" and the new hire will bug out once they've had enough time to realize they were duped. So that's fun.