Legal Question in Landlord & Tenant Law in California

There is case law and it is the opinion of some experienced landlord-tenant attorneys that the amount of a late fee must be reasonably related to the amount of damages suffered by the landlord if the rent is not paid on time [cost of additional reminders to tenant that rent due, loss of interest on the money that would have been paid, costs actually incurred, etc.]. Ask the landlord why he/she is charging as much as they intend to and what would be a reasonable price than all can agree to.