Most decent jobs nowadays require more than just an ordinary three year bachelors degree .

I do not think this is true if you have a decent skill-set. I was working a decent job, well-paid, full-time etc before I graduated from University.

I know many people who have great jobs who have only a bachelor's degree.

Tradespeople do not make a mint immediately post-apprenticeship, either. They usually have to spend more time studying etc.

Also, don't you get paid like $10/hr as an apprentice? I was probably out-earning most apprentices when I was doing like 20hrs of retail work in my first year of Uni.

you can start the classroom component as part of your year 11 and 12 studies

I think this would depend on where you went to school. Lots of schools in metro areas don't offer vocational courses, so you kind of have to stick it out till year 11 or 12, then leave, and then start your apprenticeship.

I think it would behoove most people to complete Yr12 in terms of skills and cognitive development.