for entry at the immigration in Thailand you have to show in cash if they ask. What you are talking is for get the visa, and not for the entry. And this is law....since about 3 years
Doesn't matter you've been asked before or not, it is a law to carry THB 20'000 in Cash with you, this can be another currency than Thai Baht as well, no matter, just need to be in cash. If you never been asked, you just were lucky....