So in NZ, we can import a car pre 56 and if they weren't originally fitted with belts then we don't need to install them if we don't want to.
The kicker is, if we do choose to install them, then we have to get them certified and meet certain standards, which then all costs around $600 - $700 for the cert, plus the cost of the belts, go figure.
This goes with all vehicles 56 onwards, where they must have at minimum 3 point static lap & diagonal unless there is no structure for these like hardtops & convertibles, where lap belts are allowed.
Then if you can prove that the belts in the car were factory fitted (my 62 front only) then no compliance need "IF" the original belts are still fitted and fit for purpose.
To install rear belts, then compliance is need. So F_ _ked up. Similar if changing out front brakes from drum to disc
Gav