The median income in NZ is about $66k a year ($1,273 * 52). This means half of full time employed people earn less than $31.83 an hour (assuming 40 hour weeks - the median is even worse if you assume more hours).

If you're not a qualified builder, even if you've been working on job sites for 20 years, $30 an hour isn't too bad.

But on all your points other than money, I have heard similar things. I'm not sure what we can do about the attitude problem, as a country, in order to make the trades more attractive to young people.