Ernesto Galvanmaybe because they will get a 30 day visa exemption ? And maybe because they have several months to look at other options ? The 60 day TV been the most fitting and takes less than 14 days to receive.
can still go and enjoy the visa free 30 days on arrival.. this can also be extended.. I am sure once in Thailand you will be able to arrange something. Maybe fly out after 30 days and get a simple 60 day tourist visa in a neighbouring country . At least you won't miss the birthday .. good luck