"I used to work at a large chain supermarket with something like 500 staff. It was more like a knock-on effect of selfishness/cheapness/rule-making frenzies that caused issues.
So first, we had this rule that if you bought something to eat for your lunch from the store, you had to keep the receipt and get a supervisor staff member to sign to say they witnessed you purchase it. This was to prevent people from stealing food, although I'm not sure if this had ever actually been a problem, or if the rule even helped. The whole process took half your break sometimes since the supervisors were always busy and didn't even have a pen half of the time. So people would just buy their lunch and get whoever checked them out to promise to back them up if they got called out.
Then we got a new supervisor from another store. She decided that this would now be strictly enforced with security guards at the foot of the stairs up to the staff areas, searching everyone's bags. This led to queues for EVERYONE entering or exiting the staff area. It meant that lots of people got penalized for being late to clock into their shift, back from break, etc. and anyone who did follow the rules and get their receipt signed would not have time to eat whatever they bought.
Security was even sanctioned to randomly search lockers for possible stolen food/goods. They had to pull you off the shop floor for this too, and some supervisors even tried to get the affected members of staff to clock out for the process (which turned out to be pretty illegal, so it turned into a whole thing).
Some people started getting really upset with this, and did one of two things:
They went to the McDonald's opposite the store on their break. They often had to queue, and there was no discount, but at least they'd get to eat. Management didn't like people leaving the store though, since it made things difficult in case of a fire and any other emergency. Plus there were now burger wrappers and stuff clogging up all the bins. So they banned people from being able to leave the store on their breaks. This led to parking tickets because people couldn't move their cars (max 4 hours stay, with no special provisions for staff). It also led back to the stairs queue, and people to get disciplinary actions taken against them if they left to go to their bank or take a phone call outside or whatever.
People brought their own lunches. This lead to even worse problems:
A) Most people who worked there also did their grocery shopping there due to the 10% discount. Even if they didn't, the security guards searching bags didn't have any proof that people weren't just buying/stealing food from the store than throwing them in a lunch box. So people either started doing exactly that and just taking an empty lunch box to work with them to fill, or they would start bringing their grocery receipts with them to work. Security was forced to go through the receipts and check off the items on them, so more queues.
B) Previously, the only people bringing a packed lunch had been human resources and management, so there was only a single large fridge in the break area. Now all the checkout and floor staff were bringing packed lunches, there wasn't enough room for everyone. Since management and human resources typically worked 9-5, and floor staff could start work any time from 5:30 am, this led to outrage since management/human resources felt they should have exclusive access to the limited space. So rather than buy additional fridges, they moved the fridge into the human resources office. This office was locked until 9 am when they started, and the regular staff wasn't allowed to enter without a 'valid' reason. This peeved a lot of people off, naturally, but worse than that, since this all began in the summer months, people that brought a packed lunch started getting sick. Turns out that storing things such as yogurt and meat sandwiches in an unconditioned locker room under everyone's coats and bags, RIGHT by the radiator is not such a good idea. People were calling in sick with food poisoning or diarrhea. Which leads to...
More absences from food poisoning and diarrhea meant management decided to crack down on calling in sick. The new rules were that all sickness absence had to be accompanied by a doctor's note, no matter what. Since food poisoning tends to last only a day, and the National Health Service wait times are more like two weeks for a doctor's appointment, people were getting disciplinary hearings for not bringing notes.
Additionally, there was a three-strikes policy on calling in sick. Basically, if you called in once and took a week, it was the same as calling in for a day. So even though there was no sick pay, a lot of people took multiple days, or even multiple weeks off, since they would get the same punishment anyway, and a lot of staff were college students who didn't care that much. So they were ending up with fewer instances of calling in sick, but higher rates of absences overall.
So management decided supervisors were now going to be sent on home visits to repeat offenders to ensure they were actually sick. Luckily, this only got as far as day one. One of the first people who visited happened to be in the union, which most of us hadn't joined due to the cost. She was super sick from dialysis treatments and absolutely furious, she called in her union rep and recounted everything that had been happening (along with a bunch of other stuff I haven't mentioned).
The union came in, and boy, did they have some things to do. A ton of management got moved around/sacked, thousands were spent on new break room stuff, including fridges and vending machines, and most of the previous rules were overturned. Even the store manager got replaced. The three-strikes rule remained, but home visits were no longer allowed, and no doctor's notes were required for calling in sick for less than three days. There was an exception with diarrhea since we worked with food, where you would have to get a doctor's note regardless, so most people would just lie about what their illness was.
Basically, one power-hungry supervisor that decided to start over-enforcing a rule nobody cared about caused a huge conflict."