I suspect that in reality this check on proof of funds will only happen when some other factor has already alerted an IO and they decide further investigation is warranted. Which is actually the case now. After 20 years of going in and out of Thailand at least 6 times a year, I have never been asked for proof of funds. It may be a different case for visa on arrival. Those people are already subject to at least some kind of superficial screening and perhaps proof of funds will form a more significant part in future. Whether there is a need to show cash or simply documentation, every entry is subject to the assessment of an IO, so there is always an element of ambiguity. An IO assesses the evidence in front of them and together with advice from superiors, makes a decision based of all factors in front of them. I can’t see that any normal traveller is going to face any issues because they show bank statements, bank phone apps, and bank cards, rather than wads of cash. In any case. 10k baht is about 200quid, it’s not a lot.