This one was specifically a comment about "zero risk" on MRI, it's not true. Low risk, sure. But people have been hurt.
I also suspect any clinician is going to look askance at a low risk action that isn't necessary, but the potential liability is the kicker here.
Nothing is totally risk free, but compared to most medical procedures--and most activities of daily living--MRIs are a walk in the park. For a subject with no implanted devices, I would bet the drive to the scan center is much more dangerous. I just flipped through MAUDE (https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/d...) and I couldn't find any adverse events that were more severe than a small burn or blister.
There have been deaths of course, also, but not due to normal operation.