A PSA of 12 is pretty far past the threshold for an MRI (don’t know about a PET scan) and an MRI would be pretty determinative about whether or not a biopsy is warranted. A biopsy would be pretty good at identifying cancer.
Sounds like either there are complicating factors or an absence of standard protocol adherence.
US health insurance is a mess, but that doesn’t sound like the entire story. I suspect urologists see a fair amount of friction for routine procedures related to prostrate health.