Hi Trumpy,
Here in Scotland, Building Standards (Scotland) Regulations 1990, have statutory requirements for the minimum number of socket outlets to be provided in each dwelling.

Minimum requirements are:
Kitchen: 6 socket outlets (i.e. 3 twin skts.)
Each apartment *: 4 socket outlets.
Plus 4 additional socket outlets elsewhere.

* The term apartment here refers to an occupied room e.g. bedroom, lounge.

These are absolute minimum requirements, which are clearly inadequate for the average modern house, which will usually have more outlets.

In new housing, the Local Authority Building Control Dept. would insist on the minimum socket provision before issuing a Completion Certificate.
Where the Local Authority give Home Improvement Grants to home owners, in respect of sub standard electrical installations, these minimum requirements are also enforced.
When I carry out rewirng of older properties, I always insist at least minimum numbers are installed, regardless of whether a Grant is involved.

What, if any are the minimum requirements in NZ?

Are there any minimum requirements in European countries? I've noticed, when on holiday that there seem to be fewer sockets than in UK, & mostly singles.