Residential electricity service from PG&E has never properly separated the fixed costs of service delivery to a location (maintaining poles, transformers, and wires) from the cost of marginal energy consumption. It has folded much of the fixed infrastructure costs into the per-kilowatt-hour unit price. This functions as an implicit subsidy for households that need grid tied electrical service but do not consume much electricity from the grid.
These implicit subsidies used to mostly benefit lower-income households (though not always: properties like seasonal vacation houses also benefited). Now, higher-income households are more likely to benefit from this structure because they are more likely to install rooftop solar (reducing kWh consumption) but still need the grid to work at night. Crediting solar households for grid exports makes this problem especially acute but it would also exist even if solar households were merely reducing the kWh drawn from the grid during daytime.
One remedy could be to fully separate the costs of fixed infrastructure from per-kWh unit charges and set prices directly proportional to costs. But that is probably politically unfeasible because there will be outcry that prices proportional to costs would hurt low-income, low-consumption households.
Another way to remedy it would use the previous approach but give offsetting vouchers to households that would face financial hardship as a result of the change in pricing structure. I don't know why the underlying issue has remained unaddressed in favor of patchy solar-specific changes to the law.