I think you will find that many Thai immigration officers refer to extension of stays as visas as it is more convenient to say, but that doesn't alter the reality of what they are.
What I'm trying to prevent with this extended discussion is someone thinking that they need to transfer their visa to their new passport. They don't. In fact, they can't as immigration won't do it for them. Immigration will tell them they need both passports until the visa in the old passport expires. So if you stay in Thailand on a visa rather than an extension of stay, there's no reason for you to go to immigration to have your visa transferred to your new passport. It won't happen. It doesn't need to happen. It will save you an unnecessary trip to immigration.
The other situation I'm trying to prevent is someone standing in front of an immigration officer with their new passport and trying to gain entry into Thailand and wondering why the immigration officer is asking to see their still valid original paper sticker in their previous passport. That is why you carry both passports until your valid visa in your old passport expires. Without being able to show that visa, you won't be getting entry to Thailand on the basis and terms of that visa.
Again, does your son travel with one or two passports? If one I can see that something was achieved in the transfer (although still doubt it is in fact possible to do). If he still has to travel with two passports then concerning the visa, I don't see what has been achieved.
Is it possible that you are confusing information about the visa, rather than the visa itself?
I'm looking at my new passport, specifically the first two pages. I had immigration transfer my extension of stay from the old to the new passport. In addition, there is a stamp stating when my last Thai visa was issued (years and years ago, not even close to being valid). Also, the entry stamp when I was admitted to Thailand under that long ago expired visa. My extension of stay, of course. And finally, the entry stamp when I was admitted to Thailand under that latest extension of stay.
If I wanted to actually use that visa (which of course, I could not as it expired many years ago) I would have had to travel with my previous passport which contained the original visa, but only while it was unexpired.
When a visa is issued it is put into your current passport and remains there. It does not get transferred to your new passport. While it is still valid you can use it in conjunction with your current passport. Once your visa expires, of course, you no longer need to carry your previous passport.
I think if your son (or anyone else for that matter) tried to use the visa that is referenced in your new passport rather than the actual visa that exists in your previous invalidated passport, he would not be successful. Immigration would demand to see the original visa in the previous passport. Therefore, he would need to carry both his previous and current passports. The notation in your son's new passport does not constitute a valid visa. That valid visa exists in his previous (invalidated) passport. The previous passport has been invalidated (e.g., punched or corner cut off), but any valid visas can still be used until they expire.
The extension of stay that was transferred to my new passport is in fact of equivalent status to my extension of stay in my old passport. In that sense, it can be said to be transferred. I do not need to carry my old passport to show anyone my original extension of stay. That is not the case with visas. With visas, you have to carry your old passport with a currently valid visa until that visa is no longer valid. It is not enough to carry your new passport if you are relying on an unexpired visa in your old passport.
Many people never have their existing valid visa transferred to their new passport (if this is even possible) and continue to use both passports for travel until the visa in the older passport has expired. That is the normal routine in my understanding.
Again, the situation is different for extensions of stay (inked into your passport by a Thai immigration office located within Thailand).
"His actual visa is in his old passport *and* his new passport." First I've ever heard of Thai immigration transferring a visa (not an extension of stay) into a new passport.
A visa is generally a full-page sticker issued by a Thai embassy or consulate that is pasted into your passport. What about the visa has been transferred into your son's new passport?
Does your son need to travel with both of his passports (until the visa in the old one expires) or only with his latest passport?
visas aren't transferred (you can continue to use it during its period of validity in the old passport in conjunction with your new passport). Extensions of stay are transferred (or more accurately, a record of your having an extension of stay is transferred from your old to your new passport).
Therefore, if you have an extension of stay go to immigration to have it transferred. If you only have a visa, then you can't have it transferred but continue to use both passports until the visa expires.
I believe all US passports issued through US Embassy Bangkok automatically get the 50-page (largest) passport, but if you are asked during the process definitely opt for that option.
Maybe one day Laos will start using e-Visas as some other countries use.
Everything is done by mail. Using an agent is a complete waste of money. Just follow the instructions exactly and you should have your new passport mailed to you in anywhere from six to eight weeks (possibly sooner):
They can certainly do that. I've been doing that with my Schwab account for about 7 years and no problem. But there could be a problem in the future. Just because they don't care today doesn't mean they won't care one day.