Live in Cali, Does PSA regulate complete uppers and only send to FFL?

why is it some online retailers can ship directly to your house and some others cant, i tried to place a order with PSA, and it wants to ship my uppers directly to a FFL. Now i haven't been up to date on some things but last time i did a FFL transfer for lowers, it cost me $100 each transfer. If i have to do a transfer with all the uppers it seems like a pricy way of doing it. Any advice?