You notice them because they think more about the relationships that follow that are far more important than the "getting" married process. Please give advice to the foreigners, not just what is actually (traditionially) only symbolic, but the great number of relationships that will fail; doesn't matter the reason, before they even think about marriage or giving pots of money away, especially in Thailand and where there are significant age gaps between them.
In the OP, the girl gets B500,000 and the parents get B500,000 - for "safekeeping" - HaHa! And if the relationship fails he has to say goodbye to that and maybe to half his remaining assets as well. Bad news at the beginning - bad news at the end - but only for the man - now, HE is a real loser! Plenty of stories abound!
Would you fall for such a dumb deal??
I respect Thai tradition but I won't be a slave to it! I am not a slave to my English traditions either.