I don't think it necessarily has to be in exact order, but if we ever show up and there's a big crowd already there waiting, we just hang back and let everyone else get on. I know there really aren't any rules but it should be common courtesy to let at least some of the others that have been waiting on first.That's ridiculous. But how do you know who got there first if you're sitting? How do you keep the order? I'd rather stand and wait and ensure my place in line. Pop has the corrals and I prefer that.
Since we are complaining, I hate when there's standing room only and a family with a stroller and babies gets on. Then my husband feels compelled to give up his seat because he's watching them try to balance and hold a baby. My husband has a bad ankle and the standing still on it is torture for him sometimes. (It doesn't hurt as much walking as it does just standing there putting weight on it.) We wait for a bus to sit if his ankle is acting up. But there's no way he's going to stay seated while a mom stands up with a baby. I say wait for the next bus if you have babies. It's not fair to the other people who got seats first.
The seats are another big reason I don't like taking the buses. I don't mind standing and would like to give up my seat when needed but have had experiences where someone is either too nice or acts offended when you offer your seat, so it's an awkward situation sometimes to ask unless it's very clear they need to sit.