[esotericn]

A part-time/ZHC worker in the UK doesn't work a set number of days a week.

They're assigned a variable number of hours per week. It might be 4 this week, 20 the next, 0 after that, etc.

You wait for the rota and work what you've been assigned.

It's kind of like a lower-level version of being on call.

It only really even works in the first place because we have all sorts of insane welfare subsidies that mean people have their income topped up to make up the shortfall.

I would imagine something like this must exist in the US. A quick google brought up https://www.governing.com/topics/mgmt/gov-work-irregular-hou... which sounds basically like what exists here.