Hello and welcome,
The Vehicle Code would normally be irrelevant to this situation as it is within the discretion of the employer and the customer to require that individuals driving the cart are licensed drivers who are insured as a term or condition of employment on this contract.
Providing such information does not make the guards/employees liable for any damages that are sustained, but apparently represents assurances the customer is requiring from the employer that the employees are qualified based on their own standards.
If the customer requires this information as a condition of permitting employees to drive the cart, then they can refuse to permit individuals who cannot or do not present such proof to use the carts/work for the customer.
I hope you found my answer helpful, even if the law is not in your favor; please click on the GREEN ACCEPT button above for my answer. This is necessary for me to be paid for my work and so that I can get credit for assisting you. Your question will not close, and you will still have the opportunity to follow-up if needed. Leaving a bonus and positive feedback is not required, but doing so is certainly appreciated!
If you have additional questions, please keep in mind that I do not know what you already know or don't know, or with what you need help, unless you tell me. Please consider that I am answering the question or question that is posed in your posting based upon my reading of your post and sometimes misunderstandings can occur. If I did not answer the question you thought you were asking, please respond with the specific question you wanted answered.
Also remember, sometimes the law does not support what we want it to support, but that is not the fault of the person answering the question, so please be courteous. Thank you.