Depending on you passport, to enter Vietnam you will need a visa. The online form requires your return ticket information. It is best not to lie. I was asked to show my ticket at check-in. Book for 30 days out with an exchangeable ticket.
I think you are missing the point. Maybe you should tell the government how to advertise or what rhey to do. At the end of the day, it is a privilege, not "a right" to stay here. They can do as they please. Look at what is happening in the States. Even Americans are being hassled at entry. Take nothing for granted, especially in a foreign country.
When in doubt or for clarity, contact a local lawyer that specilizes in immigration, not Facebook University.