I think they BMW rider are restricted physically from nodding, by way of a neck brace.
installed buy Beemer dealers upon signing the finance agreement, for the purposes of when service and repairs are required, the owner can't see to find his wallet. then the dealer offers to 'find' it and 'relieve' the owner of the required amount of funds without worrying the owner about the actual total value.
thus the owners believing that the BMW brand is wholly value for money, and only finds out the true cost of the services and repairs when the AA bloke takes the brace off to show the owner the damage the main/rear/final drive seal/ gearbox/ electrical/ ABS/ Clutch ect ect related failure.
Think, you never find an owner talking about how crap their bike is... but past owners tend to call them crap, expensive and unreliable...
did once get a nod from an owner, was so shocked I wobbled and nearly fell off!... he must have been on a test ride and not had the brace installed yet!