Vietnam is easy, they don't want the ire of the US. They're threading the needle of getting US support because the US + China are unfriendly while not upsetting anyone too much.

Some members of BRICS are currently taking part in sanctions against DPRK and aren't likely to stop as they don't want to give up trade with the US or Europe for it, so their application would be rejected as it requires all 5 founding members to agree to the application until a new criteria system is official.

I don't know enough about Laos to guess.