I can confirm it does, and there is nothing inaccurate in the advice from the poster you have quoted. The driver of a vehicle which I have access to forgot to pay the drop off fee at an airport last year and despite them contacting the operator prior to the PCN being issued, was told it was too late and the PCN was issued. The registered keeper wrote a similar (but less rude) email to the parking scheme operator and the ticket was written off.
In effect, when wheel clamping vehicles on private land was made illegal in England in 2012, the government changed the law to make it easier for private parking companies to recover unpaid parking charges from the registered keeper where they cannot identify the driver. However this law cannot be used on land which has statutory parking controls. As many airports have byelaws which amongst other things, criminalise certain type of parking offences, they thus cannot rely on this law. Despite your assertion, Gatwick is no exception, with sections 5 and 6 of the byelaws criminalising various motor vehicle actions.
You are correct in that it is not a sure fire way to avoid paying given the driver of the vehicle still remains liable, but given these companies don’t readily have the wherewithal to carry out investigations into who the driver was, they will just write the ticket off.