How to avoid paying the new combined carry on luggage weight excess charges

I had never heard of this new combined carry on baggage weight before - until this morning. My wife's handbag and my small briefcase meant we were 4 kgs over the 14kg allowed between us - so got pinged $60. Good for one good all you say. Well sadly NO - as this new rule is not consistent (especially to some of the backpackers I observed ) as some have found clever way to beat the hand luggage weighing system and have got it down patt.
Here's how it works - they wait until the Final Boarding and even when staff begin calling the passengers name - so they then come rushing down to check in counter because now there's panic about flight departure and just no time to weigh any luggage - can't hold up departure.!
Very clever.

Domestic
Australia-Cairns
Australia-Gold Coast