That's quite surprising really! I thought they'd be more strict there than they are here.
Here if you have aftermarket mechanical type mods, cage, race seats, belts, anything like that, they all have to be certified before going for your warrant of fitness and each time you make more mods have to be added to the cert plate before the next WOF. They're pretty strict here about that stuff and take great delight in dealing to those that haven't adhered to the rules. Mind you, if you haven't adhered to the rules, then your insurance is void too.