9-0 rulings happen all the time. I couldn't find an easy to consume list so I asked AI to provide the percentage and it said 65–75% of rulings in a term are 9-0.

I believe it's the second half of parent's comment that is doing the heavy lifting.

A 9-0 ruling written by Clarence Thomas which puts basic human rights (internet access) above civil liability - try asking a chatbot to find many of those.

I think around 50% are 9-0 and then 30% are either 7-2 or 8-1. The contentious cases are the remainder.