There’s no recourse if you’re uncertain. You can’t wave over a manager - you’re expected to process the huge queue with more piling in all day.
You work multiple long shifts per week. In a single shift you make thousands of decisions with huge impact to your life going forward - huge downsides for mistakes.
When you make 1000 decisions in a shift, even a 0.1% error rate is one wrong decision per shift!
And even if you are a nice person, you need to keep your job. When your biggest boss has an unsympathetic streak, you tip more into “my mistakes will be punished” mode.