tired
zero hours means there are no promised hours or schedule. You might regularly be scheduled to perfect hours at the perfect timings. You might not get scheduled at all, or anything in between. Managers often cant be bothered to deal with holiday requests meaning people are left trying to scramble to get coverage for a day they requested but wasnt scheduled. Or the manager will approve it after the fact and write in a sub, and if the sub already wrote down their hours, they are now in the shit for not knowing avout the change. It also means people just dont show up, and others work late (possibly unpaid as Ops daughter reports) as they arent on the schedule.
Even when they honor your time off request, I am convinced many managers only know how to copy paste in order to create a schedule, they dont build it based on promised hours, requested days off, and knowing that some workers have better skills for certain situations (like a party at a resteraunt, or making sure not to have a shift with nothing but inexperienced new hires). so if you finally have had regular hours because of seniority, and request and receive a day off, that hole in your schedule will persist until the new person on the day needs a day off, and you manage to get yourself slotted back in instead of some random untrained new person.
It isnt anything like 'part-time' work was in the old days. When I was a teen it was posible for mothers to work lunch shifts only, and teens to get afternoons and weekends and college students or other adults needing a second job to get late nights. There were also some few who worked full-time, bridging between the gaps of the parttimers in what should be slow business times. They had more staff, but the staff was more reliable because their hours worked with their time available. Businessess unable to offer full time hours acccepted that they had to take part timers when the part timers were available.
Nowadays they hire fewer and make no allowances for their lives when scheduling. Everyone is looked down on as if being a less than full time worker means they should grovel and be grateful. My teenaged daughters would find themselves scheduled for day shifts, or past midnight on a weeknight. Mothers with school aged children would be on for afternoons, nights and weekends. The workers were often left swapping shifts and rescheduling themselves to solve these problems, but then sometimes faced a manager who wouldnt agree to the changes. That would almost always end in people quitting because school, or their real job, or the fact that part time irregular child care on short notice is not a thing that exists at any price much less one that can be paid by resteraunt and shop workers, and the remaining workers schedule gets even worse.
Oh, that was a rant. That felt good.