EM Resident here. I get what you're saying, and mostly agree -- in the community especially, there aren't a lot of really compelling reasons to use regional blocks given the time it takes to do, the lack of an ability to bill for it (in most settings), and the concerns raised in this thread by our anesthesia colleagues / other services that might have concerns with the "loss of the neuro exam" in a fracture case, or whatever. However, I disagree that regional anesthesia is outside the scope of our practice, and think there's tons of examples of how it is certainly useful in EM daily practice.
The blocks I use the most are digital blocks, nerve blocks for complex lacerations on the forearm, and as an adjunct for pain control in hip fractures. I also use blocks for dental pain and for facial lacerations when I don't want to disrupt the anatomy before a repair. All of these can be done using a landmark-based approach, but (at least for the extremities), your precision is improved with ultrasound. We also tend to use lidocaine instead of bupiv which reduces the likelihood of many of the serious complications that occur with regional anesthesia.
All that said, there are a lot of useful applications for ultrasound-guided regional blocks, and the knowledge is becoming more and more widespread and adopted -- but as you said, I think it's generally at academic shops where residents are curious and have the time/interest to do this and aren't thinking as much about their RVUs or moving patients. A leader in the field from EM is Andrew Herring at Highland, who runs this website:
Welcome and promotes this as a way to improve patient care.
While it may be in the future that people try to start billing for these procedures, and who knows, maybe someone will decide (Herring has published on this) that we can/should be placing catheters, for the time being I think plenty of people are already doing this safely without any instruction from anesthesiologists every day as part of their practice. I doubt this trend will reverse itself.