Title on HN should probably read "University of Cincinnati" rather than UC. Even I, a graduate of University of Cincinnati now first thought "University of California." (Admittedly I live in California now)
berkeley.edu (where "University of CA" is a subtitle), ucla.edu, ucdavis.edu, etc.
Also, Berkeley was the first real UC campus.
I think Berkeley has its own bare domain because their name was registered before the UC naming conventions were established. I'm pretty sure it was the first or second name registered. https://bind9.readthedocs.io/en/v9_16_5/history.html
Not sure of that, though- in the old HOSTS.TXT predating DNS, UC Berkeley was called UCB, and the server ucbvax became ucbvax.berkeley.edu.
I think it's funny now they teach classes at Berkeley about stuff (DNS, nuclear energy) and the research was done just 30-70 years ago right on the same spot!