The Interstate Commerce Clause says that the federal government has the constitutional authority to regulate interstate commerce, which likely means the federal

The Interstate Commerce Clause says that the federal government has the constitutional authority to regulate interstate commerce, which likely means the federal government could prohibit California from doing this (I say "likely" because "interstate commerce" is complicated and has a long history of court cases). It doesn't say that no state can make any rules whatsoever that affect interstate commerce. Plenty of states have plenty of regulations in place for interstate commerce, including obvious things like inspections at state borders.