No, they were at Suvarnabhumi Airport trying to board the Lao Airlines (QV) flight to Vientiane, Laos....and, they were tentatively scheduled to have a return flight back to Suvarnabhumi Airport from Vientiane
FYI— This has nothing to do with Thai E–Visa's, Thai Visa Exemption free stamp (ผ.60-ม.17), or even the 15 countries eligible for Thai Visa on Arrival (Thai VoA)
The Lao Airlines (QV) check-in counter staff at Suvarnabhumi Airport have been known to be quite zealous and going beyond their assigned duties as only hired ground staff for an airline and they are NOT Lao Immigration Officers/Officials....
Thai Airways (TG) or Bangkok Airways (PG) at Suvarnabhumi Airport or Thai AirAsia (FD) at Don Meuang Airport are not as zealous as sometimes the Lao Airlines (QV) check-in counter staff at Suvarnabhumi Airport can be about Lao Entry requirements
Alternatively, you can catch a domestic flight to Udon Thani (UTH) and make an overland crossing at the Friendship Bridge land border (Nong Khai)
or, catch an overnight train from Krungthep Apiwat Central Train Station at Bang Sue (Bangkok), either the train going to Khamsavath Station at Vientiane, or the more comfortable train to Nong Khai, then a short wait for and catch train that goes to Khamsavath Station in Vientiane at Nong Khai Station
The price for a Lao Visa on Arrival (Lao VoA) is USD $40 Dollars (using pristine "new" condition US Dollar Banknotes) for all passports except China and Vietnam, and, there are a few countries that cannot obtain a Lao VoA and must get a Lao Visa Sticker from a Lao Embassy/Lao Consulate beforehand
Also, regarding the price of a Lao VoA, any other currency used is at the discretion of the Lao Immigration Officer issuing a Lao VoA and will not be at a favorable exchange rate price, such as ฿1900 Thai Baht (vs. e.g., ฿1200 or ฿1300 Thai Baht at current exchange rates for USD $40)
the Thai Consulate in Sydney is asking for THAI immigration Entry/Exit ink stamps from Thailand and NOT Australian immigration Entry/Exit ink stamps from Australia
if you go to the Australian Border Force counters after the immigration gates (there should be a large group of Border Force officers, then anyone can ask for Australian Entry/Exit ink stamps in their passport
Do note, these Australian Border Force counters are BEFORE Baggage Claim carousels, but after the immigration gates
As the foreign guest staying at whatever type of accommodation, the guest doesn't need to do anything (except provide their passport information details), but the property owner (house/condo/villa/hotel/resort/hostel/motel owner) is responsible to report and would file a TM30 for that foreign guest staying at their property (hotel, house, villa, condo, hostel, resort, etc.) and doesn't involve the foreign guest going to a local Thai Immigration Office or anywhere to file a TM30 Report
The property owner can file a TM30 online
Also, it doesn't necessarily have to be the property owner, but a representative or someone who has all the necessary property ownership paperwork can file a TM30 for the foreign guest staying at the property/accomodation