Dayton freight right around the corner from us pays part time dock $20/hrFour Hour Casuals get an 8-hr Guarantee if they work over 4 hours, which they often do at our barn, for a half hour or 45 minutes, sometimes longer. That's about $19/hr. for 4-1/2 hours.
I do not know of any of the non-union gigs that pay an 8 hour guarantee. Most of our 4-hour Casuals are College and it works out well for them.