So, it's a legal requirement to have one or the other I guess... that seems slightly more reasonable.
Reminds me of a run in I had with a Garda many years ago up in Phibsboro. I had an Opel Astra (& Mrs Catcher had a petrol version of the same car) with a faulty headlight switch so I installed a regular 3 gang hall light switch in it's place (borrowing the switch from Mrs Catchers car for the NCT)... anywaysanall the Garda looks in the window and spots the switch so asks what's that contraption... a motor vehicle, says I... that contraption, says he, pointing at the switch... oh, a switch, says I... what does it do, says he... at the risk of stating the obvious it switches electrical equipment on and off, says I... pull over there, says he... checked that all my lights worked and then took my details saying he was going to check the legality of the switch... grand, says I, it'll be interesting to find out what a switch is legally required to do... never heard from him again.