First grocery job was for a huge union closed shop (#2 largest grocery in US) and then 2 years later, I moved to a non-union shop that was opening a new set of stores.
I made more money at the non-union shop, but there were very strong labor laws in the state and they couldn’t do a ton of union busting. They had successfully ~10 years earlier fought off a union drive and I actually think that’s why benefits + pay were pretty good (tuition reimbursement, etc) over fear of organizing.
First day that the new store opened, 50 of the newly hired employees called out sick and demonstrated in the parking lot of the store. Apparently they were workers from the union shop paid by UFCW to get hired by the new store, go through training, and then wear their employee uniforms out on the demonstration line and never show up to work.
It was badass, and also maddening. But I made so much money because they gave us unlimited overtime to make up for the 50+ employees who didn’t show up ever again.