I feel ya. I failed my test the first time for two reasons...I was impeding traffic by going too slow and I wasn't willing to run over a squirrel.
They failed me and said they have never had to tell a teenager to go faster and that I needed more time to learn before going out on my own because I would get eaten alive on the roads. I was the first person they failed for going too slow.
The reason I was going too slow was they took me through a neighborhood initially then onto a main street but we never passed a speed limit sign for the whole test so I had no idea what the speed limits were. It didn't help that I didn't live in or even near a typical neighborhood..the street right in front of the house I lived in at the time had a 40 MPH speed limit.
Rule of thumb for me now is typical neighborhoods are 25 MPH unless I see or know otherwise since there are places like that were I live. It was valid to fail me...even if a tiny bit unfair.