Doctors note

Do we have to have doctors notes if we miss any days of work for being sick? I would understand it from a high end job but getting paid 9$ an hour does not seem like I’d have to have a doctors note for 2 4hour shifts. For context I got really sick and was scheduled two days in a row both being 9am-1:30, I tried to thought it out the first day and then the next two days I physically couldn’t. I told them I didn’t have health insurance and that it would take me working 30 hours to just be able to afford a visit to the clinic. What’s weird though is that we’ve had people call in 30 minutes before their shift and say they were going to the eye doctors on a Saturday at 5 pm and they didn’t say anything we’ve also had people call in for being “too tired” and also had people call in for being sick so it was weird that I called in an hour before my shift and they got mad. My manager was telling me I HAD to have a doctors note for the first day even after I explained that’s it’s expensive and she said “idk” IDK????? and so I kinda missed the second day out of spite because of how rude she was to me and I’ve been wanting to quit anyways cause I got a better job but I thought that it was just crazy that I’d have to have a doctors note but no other employee has had too or when they show up they just sit in the office the whole time cause their sick.