Nail biter

Someone who is afraid to make decisions due to disproportional fear of the consequences.

I realized I had forgot my ID after I was already standing in line with a 6-pack of IPA.

Luckily, I was in the lane with a familiar grocery cashier who had sold me beer numerous times.

When asked for ID I politely said "hey sorry I just realized I forgot it" .
The cashier nervously looks at me then turns around to her manager and says "a customer is here who I have sold to before but they forgot their ID this time" .
To my displeasure, the manager lets me know I cannot be sold the beer without an ID.
The cashier in this example is a nail biter.