
In a commercial landlord-tenant relationship, the rights and responsibilities should be spelled out in the contract. It's possible some contracts prohibit the landlord from denying access to anyone approved by the tenant. Others may retain that right for the landlord, or specify the circumstances when the landlord may restrict access for someone approved by the tenant.
To step outside SB321 which is a hot button for some people, a landlord could theoretically prohibit parking if a vehicle does not have current registration and inspection stickers. I know a residential landlord who does that. Even if someone has an access card, that landlord reserves the right to tow vehicles with expired inspection stickers. So I think it's theoretically possible some landlords have the right under some leases to prohibit vehicles or people for other reasons too. Completely hypothetically, refusal to allow a search could be one such reason.