The boyfriends standing there for the whole shift does sound bizarre. Maybe they were chatting with the cashiers the whole time and of course that wouldn't be okay
Well you're supposed to be at work. To your employer or to customers it might look like you're distracted and unprofessional, which would reflect badly on the store.
Did you assume I'm American for some reason? I'm just talking about being professional at the work place and focusing on the work during it, a store wouldn't like people chitchatting with their boyfriend the whole day where I live (Finland) either.
First of all, it's an entire different things. There were people standing in areas they weren't supposed to be standing in, possibly distracting the employee. Second of all, two things can be shitty - the cashiers having their boyfriends there all the time, and the bosses wanting a cashier to stand all the time. One doesn't make the other worse or better, it's just whataboutism.
In the small grocery store around the corner where I live the cashier's are listening to music, having phone calls with their earplugs in or watching videos with their phones lying near the register. The work is boring and repetitive, customer interaction is quite minimal there anyway because they are really fast in ringing you up anyway. And that's everything I care about anyway. They can enjoy their day a bit more and I can get to doing what I enjoy fast, too.
I (a customer) was in a deep chitchat with a bike mechanic about some other outdoor hobby in a big US outdoor gear chain. For like 30min :-) Then I chatted about learning foreign languages (!) with the casheer.
I definitely found the experience memorable and have great association with the store's brand!!!!
I used to hang out and chat with my friends at their jobs for extended periods of time all the time when I was young. I just made sure not to interrupt or get in their way when they needed to deal with a customer. And their bosses were always cool with it.