If Cabelas has any physical connection to California then they can force the collection of sales tax if they do not then California cannot force the collection. This physical connection can include a sales location, distribution center or salesperson.
US Supreme Court ruling in the Bellas Hess case in 1967.
I am well aware of the legal situation. Cabela's has admitted to me that they have no physical presence in CA, and thus cannot be compelled by CA to collect sales tax on shipments into CA. Their stores are responding to an edict from their corporate office, which is apparently scared witless by recent cases in NY state. I have told them that I will no longer purchase from them, even though I like them and their product selection. They seem unfazed by my decision. I have learned over the years that many corporate tax departments and executive teams seem to suffer from an acute case of cranial-anal impaction.