Actually, Vientiane and Savannakhet employ a hybrid system. Despite what they claim, you need to be in Vientiane or Savannakhet when applying for your visa and you will be called in for a short interview in addition to making payment in cash, in THB, in person as well.
Apparently in Laos they're using a hybrid system where you everyone is interviewed meaning just staying in Laos isn't enough - you actually need to be in Vientiane (or Savannakhet) so they can see you in person.
The hybrid part is that you apply online, pay in person and will be interviewed as well but then you receive your visa via email.