Why do people stay on the road for more than an hour after a car is stopped for an accident?

I live in an area where there are a lot of bridges and tunnels, and sometimes accidents or flooding causes the road to be shut down temporarily. I also take a bus to school because I can't have my license yet. So I've spent many an hour in traffic caused by accidents.<br><br>The problem I have is that I see people passing the accident, and they still stay on the road. What even is that? Clearly they've seen the cars, now get off at the next exit and take a detour. It's not hard, and this could probably clear up a lot of traffic and time.<br><br>I feel like my bus driver knows this, because even if we see an accident, he'll get off soon after. And he'll sometimes say "There was an accident up ahead, so we're going to take a detour." and then we're only stuck in traffic for all of 10 minutes as opposed to an hour. I don't know, maybe there's just something I don't understand about drivers, but it just seems so illogical.