I totally agree with Lutz on this point, however there is a real problem in the UK (and possibly elsewhere) because the data plates fixed by some of the manufacturers apparently do not comply with statutory requirements and thus are not enforceable.
And that might have given some B only licence holders a problem as I outlined previously in comment #52.
Who is to blame for this mess of inadequate clarity - legally its each individual manufacturer as they are supposed to issue compliant documentation and labels etc, but also highly culpable is the NCC, who have interfered by trying to set load margins based on the e number of berths, and their insistence that NCC members should apply the NCC logo with the NCC calculated MTPLM.
Whilst I'll give the NCC the benefit of the doubt that when this process was developed it was done so to try and organise what was a cottage industry, but information and processes the NCC has been involved in producing and disseminating has made these points so difficult for many customers to understand its become a farce.
It about time the NCC revised all their advice to manufacturers and end users to directly comply with the statutory requirements, rather than offering alternative unclear information or advise with sometimes is incompatible with the regulatory requirements.
The advice should be concise, using criteria that are formally contained in the type approval information specific to that model of car or caravan, and to be used in such a way it cannot lead to an illegal conclusions. E.g. advised weight ratio's that exceed the tow vehicles load limits, and MTPLM values that mislead owners about what they have purchased - which for B licence holder might actually be beyond their licences limits. And making money for nothing when it comes to increasing MTPLM's for a payment.