I don't think Rivian attempts to compete with the major charging providers like EA, EVGo, and now Tesla. Rivian focuses primarily on the major interstate routes and "Adventure" outdoor locations (e.g., Lake Tahoe, Yosemite, Appalachian, etc.). Rivian's charging stations are spares inside major metropolitan areas (e.g., LA, San Francisco, Philly, etc.). This is their strategy, not an oversight.
Mostly, I drive the Phoenix to North Bay Area CA route. And Yes, I can make my trips entirely with Rivian charging stations. Typically, these stations are approximately 150-250 miles apart, a good match for Rivian's range.