there are also many people for whom English isn't their first language so reading and understanding the requirements themselves might prove to be too difficult. Also some very elderly or those with mobility problems might warrant using the services of an agent
it has been shared repeatedly on nearly every post about requirements to return to Thailand. I think initially it was shared from a print out of the requirements from the London Thai embassy requirements
my understanding is that returning Thais do not need a Covid test until they arrive in Thailand. They require a fit to fly certificate before leaving the country they are departing from ie no high temperature or obvious sign of respiratory illness
They could travel to Thailand with OA visas but there is an element of risk for them given that it is likely that many of their fellow travellers won't need to have a negative covid test before flying. This is only a requirement for foreign nationals. You need to weigh up the risks v benefits considering their age, along with the risk of contracting Covid-19 where they are staying now
Perhaps the owner speaks no English so has used an agent to negotiate the rental of the property with a foreigner, deal with repairs and the minutiae involved in renting out a property. The landlord in all likelihood trusts the agent and might not feel comfortable negotiating a contract with a foreigner
that is correct re the 800K only needed to be shown in your home country bank if using a non immigrant OA visa (aka retirement visa). Perhaps the OP is unaware that this visa can give them a second year at no cost if they leave the country before the first stamp ends. They would only need to buy a re-entry permit at immigration to keep this second year of the visa alive and be able to re-enter on it within a year of leaving
my friend left Australia recently to return to live in the UK, she had to show a job offer in the UK or lease or property with her name on it there or shipping receipts showing that she was relocating with the contents of her home. She was given an exemption to leave Australia. Another friend was denied permission to leave to attend her father's funeral in the UK. I guess because she and her family would have been returning to Australia after a brief stay in the UK and could potentially bring Covid back with them
there are foreigners with current retirement visas locked outside of Thailand. Some own their own homes in Thailand, have no residence in their country of origin. Some have their pets and all their worldly goods in Thailand. For them paying for two weeks in quarantine to be able to return back is undoubtedly worth it
It is a requirement to get a flight and certificate of entry (COE) which is only issued by the Thai embassy in your country. Check with them if your wife's insurance policy is adequate to meet the requirements for a certificate of entry or if you will need a separate insurance policy covering your period of stay