Their explanation regarding bus lanes ties in with my point in an earlier post about mitigating losses in that as an Enforcement Notice does not prima facie offer a discount but is for the full penalty then they see their actions in paying the discounted charge as being rational and at least cost to their customer.
However, I think they've got themselves mixed up as between private and public PCNs because the latter need only the following to be established and produced in evidence in support of reps to the effect that the registered keeper is a hire company:
4(d)the recipient is a vehicle-hire firm and—
(i)the vehicle in question was at the material time hired from that firm under a hiring agreement, and
(ii)the person hiring it had signed a statement of liability acknowledging their liability in respect of any penalty charge notice served in respect of any relevant road traffic contravention involving the vehicle during the currency of the hiring agreement;
(7) Where a recipient relies on the ground specified in paragraph (4)(d), their representations must state the name and address of the person to whom the vehicle was hired at the material time.
whereas for a private PCN, the hurdles are greater:
(a)a statement signed by or on behalf of the vehicle-hire firm to the effect that at the material time the vehicle was hired to a named person under a hire agreement;
(b)a copy of the hire agreement; and
(c)a copy of a statement of liability signed by the hirer under that hire agreement.
Note 'copy of the hire agreement'.
In practice, however, these companies accept proof less than a copy of the full hire agreement.