I'm surprised these systems pass the type approval regs, a tow bar fitting certainly has to...
Useful to note that the regulation doesn't apply to vehicles over 3500Kg. I'm not sure where it leaves motorhomes up to 3500Kg with a rear extension where the number of towbars sold for any individual make is likely to be very low in number & thus impossible to manufacture economically to meet the regs.
Towbar EC Type Approval
An EC Approved towbar will carry a plate or other durable label bearing the EC approval number plus other information including the S-Value (maximum tested noseweight) and the D-Value (the test load as calculated by EC94/20 requirements - note the D-Value is not the same as the towing capacity). The main requirements of an EC Approved towing bracket are that it is fitted to all of the towbar mounting points specified by the vehicle manufacturer, that it has undergone a rigorous testing procedure overseen by the Vehicle Certification Agency (VCA), and that production towbars are subject to Conformity of Production (CoP) to ensure that production towbars are manufactured to the same standards as required by the initial test towbar.
If your car* is registered on or after 1st August 1998 and you fit a towbar, it MUST by law be approved to EC94/20 and installed correctly according to the manufacturers' instructions. It is an offence under the vehicle Construction & Use Regulations to fit, use or permit to be used, a non-approved towbar on the vehicle
* The regulations apply to Passenger carrying vehicles up to 3500kg Gross Vehicle Weight. Light commercial vehicles are not covered by this requirement, so for instance a Ford Transit van is not required to have a Type Approved towbar even if registered after August 1998.