As it appears there was no police report, then fault will be determined by the insurance companies. They might tag this as shared 50/50 fault. Or, they might hold that the other party is at fault for failing to yield to traffic already in the roadway.
21804. (a) The driver of any vehicle about to enter or cross a
highway from any public or private property, or from an alley, shall
yield the right-of-way to all traffic, as defined in Section 620,
approaching on the highway close enough to constitute an immediate
hazard, and shall continue to yield the right-of-way to that traffic
until he or she can proceed with reasonable safety.