Can the 20,000 Baht requirement for Thai immigration be fulfilled with a money order or cashier's check?

When entering Thailand, travelers may be asked by immigration to show proof of at least 20,000 Baht. This amount must be in cash, in any currency, equivalent to 20,000 Baht, and should be carried on you upon arrival. Numerous users indicate that cash is the only acceptable form of this requirement, with no provisions for money orders or cashier's checks from Thai banks.