Owned autos: a business needs coverage for the vehicles it owns, and in California its own policy pays first on them. Under Insurance Code §11580.9(d), when two policies apply to the same vehicle, the policy that describes or rates it as an owned automobile is conclusively presumed primary and any other policy is excess. If an employee with permission crashes the company's van, the company's BAP is primary and the employee's personal auto policy is excess. In California the coverage follows the owned-auto policy, not the driver.
Hired autos: coverage for autos the business leases, hires, rents or borrows. It fits a firm with no fleet that rents vans for trade shows.
Non-owned autos: protects the business against vicarious liability when employees use their own cars on its behalf. A business needs no owned autos to buy it. Under the standard form an employee is not an insured for an auto owned by that employee or a household member, so the employee must rely on their own auto policy.
Uninsured and underinsured motorist (UM/UIM) coverage protects people in the business's vehicles when an at-fault driver has no insurance or too little. Under §11580.2(b), when the named insured is an entity, an insured means any person while in or upon, or entering or alighting from, an insured motor vehicle. So a client riding in a company van is protected.
California UM rules for a BAP:
The insurer and any named insured may delete UM coverage by a written agreement in the statutory form, and that agreement binds every insured while the policy is in force (§11580.2(a)).
The coverage is offered at the bodily injury limits, but it need not be offered above $30,000 per person and $60,000 per accident (§11580.2(m)).
UIM pays at most its limit less the amount paid by or for the person legally liable (§11580.2(p)(4)). With $100,000 of UIM and an at-fault driver whose insurer pays $30,000, the most UIM can pay is $70,000.