I think the caller to the programme was of the misguided belief that part of the 3% levy on policies includes for fire service. There does not appear to be any basis for this
I don't suppose it matters how they determine their premiums. At the end of the day, we can only compare de meerkat - and take whatever policy gives the best bang for yer punt nua.
Insurers calculate premiums to cover many things. If you have what is commonly called House Insurance, it covers you against all the perils listed in your policy. That includes fire brigade charges, it also includes engineers fees, demolition, removal of debris, legal liability protection as occupant, houseowner, and personal liability.