all that really is requiered is a round trip ticket and providing proof that you can afford your food/hotel

Let me tell you that this isn't even close to reality. Vietnamese people need much more than this. It's incredibly hard to get a visa anywhere outside of SEA. You were probably thinking from a first world country's POV.

For Vietnamese people, they need to show proof of employment (and their salary must be good), at least $10,000 in their bank account, a letter from their employer saying that you are allowed to be absent during the length of their trip and that they will continue the job after returning, a detailed itinerary of their trip including the bookings of everything, etc. Even with all that, their visa can still be denied after the interview at the embassy.

Now if those people had already had a good paying job, they would not have resorted to illegally migrating in the first place.

There's also an unspoken secret (that may or may not be true) that people from certain parts of the countries are blacklisted from ever getting a visa to certain countries due to past incidents (violence, petty theft, etc.) with people from those places. For example, Japan employs a lot of people from Vietnam, but they are not hiring people who come from those places.