If you isolated at home but your family/close contacts were still able to come and go (even if just to the supermarket or the park) the risk of the infection being transmitted into the community is increased
If you are isolating at home you do not go anywhere! End of. It is not open to discussion. Your food and deliveries are delivered to the garden or outside your front door. Medicine ditto if needed. The idea that a positive case will pop to the supermarket or the park is ridiculous.
The reason why you are using MIQs is simply because your government is hell bent on pursuing the zero covid strategy.
And instead of trusting the sensible and careful citizens (and I may add intelligent adults) of NZ and following a home isolation policy, as almost every other country in the world is doing outside of China, it is choosing to treat you all like children and locking people up. I am assuming once in the MIQ you can not simply leave if you change your mind?
Do you actually realise how disturbing that policy sounds to everyone else? You have been coaxed into believing it is for your own good which I am sure is not the case for everyone.
At what point are you likely to see suicides and breakdowns? As more and more people are unable to cope with confined isolation for long stretches - which by the way if you are also in law you will know we use isolation and segregation as a PUNISHMENT in our prisons for poor behaviour. The prisoners here are put into cells alone, given food and 30 mins daily exercise as a punishment. So you can see why it is considered to be draconian, we try to avoid inflicting this even on our prisoners because it is known to cause such harm and mental anguish, and the prisoners aren't even ill with covid! It is unimaginable to be suffering from some of the extreme effects of covid and alone in this way. For some people they will not be well enough to keep themselves clean or their surroundings or to cope with being alone for so long.
At some point someone is going to wake up and realise you can not run this kind of MIQ programme for years/decades with no consequences. It IS extremely harmful whichever way you look at it.
By the way it is also worth noting that by the time you have symptoms and are tested and given the results, the chances are the rest of your family and friends/contacts will have caught delta by then anyway, so it won't minimise spread by very much sending large volumes of people into secured facilities (with or without free will)
Not that it is even feasible to open endless MIQ as the infection spreads gennz