Respectfully, you're very wrong. Staffing and site logistics would increase four-fold to support a live production, and then you need infrastructure to support that. Yes, post could happen offsite but there are so many challenges with that disconnect in a live environment (I have a headache just thinking about it). There's a very good reason why the live versions of this show are recorded in a studio-adjacent setting.
Seven and Endemol will have modelled the costs for a live format and I can guarantee Seven laughed that off the table as soon as they saw the numbers. Live TV is expensive as fuck and this current TV landscape is too unstable to take that big of a risk.