About Placing the warning triangle when breaking down on the hard shoulder: which statement is WRONG?
The photo caption says: 'Place the warning triangle about 30 metres behind your car', with no separate rule for the motorway.
The sentence explicitly ends with '(but it is wise)'.
The hectometre marker along the motorway also shows your licence plate, which you report to roadside assistance.
'If your hazard lights are blinking and your car is clearly visible, that is not mandatory (but it is wise).' The duty only applies if the car forms an obstacle that approaching drivers cannot see in time.
Explanation
trap: data attached to the wrong source. Book p.168 - the hectometre marker only shows the road number, the hectometre reading and left/right; the licence plate is not on it and is not part of this location report