Can my wife use her Thai passport to exit Thailand without needing to renew her visa annually?

My wife holds both Thai and Australian passports. She has been told by Udon Thani Immigration that she needs to renew her visa for Thailand annually (some obscure category) and thereby report every 90 days otherwise , if she uses her Australian passport to travel to Australia, she would be fined for overstay at Bangkok airport regardless of showing her Thai passport. This is what we have been doing for 5 years. Now , I have been told that she can exit the country on her Thai passport through the new Automated system which doesn’t check for visas, providing she shows the airline both passports at check-in . If this is true, she would no longer need to renew her Thai visa and 90 day reporting . Can anyone confirm this ? Thanks.