imagine this. You decide to visit Cambodia from Thailand, less than 1 hour. The IO in Cambodia decides to deny your entry and sends you back to Switzerland. Perhaps they could check your Thai valid visa
that is not what the OP was asking. Some IOs have insisted a special letter for the 65K method. It is, or was, a special letter. NOT a statement. If you have not used the
*****
K method in leu of depositing 800k, you would never see this letter.