Do the Thai masculine & feminine "polite particles" have counterparts in Lao?

Question

In Thai there are particles which can be used at the end of many sentences to make them more polite. Different particles are used by male and female speakers:

• "ครับ" (kráp) : male
• "ค่ะ" (kâ) : female

Lao is so closely related to Thai that they are apparently mostly mutually comprehensible.

Yet one of the first things I noticed in the speech when I crossed the border from Thailand to Laos is the complete lack of such particles in Lao. I never hear anybody say them and none of the materials I've seen on Lao describe them. In Thai it's one of the first things you are taught.

• Does Lao have etymologically related words that serve other functions?
• Did Lao have them formerly but they slipped out of usage in the remote or recent past?
• Are they an innovation in Thai since after the point in time the languages diverged from their common ancestor?

Answer 1

This video from Youtube, Stories behind Polite Endings in Thai ครับ/ค่ะ and Lao, answers all of your questions. Let me write down some excerpts from there:

The polite particles came from legacy words of master/servant relations. As you know, social status and relationship of people in a conversation impacts on the style of such conversation;

Does Lao have etymologically related words that serve other functions?

Yes, these words are master, ຂ້ານ້ອຍ servant, and similar ones.

There are some usage rules, not using ຂ້ານ້ອຍ twice: e.g. "my name is John", I is already ຂ້ານ້ອຍ, so the polite particle is omitted.

Also, ເຈົ້າ ("lord") is used in meaning of "yes".

Did Lao have them formerly but they slipped out of usage in the remote or recent past?

Yes, they have been used as both pronouns and polite particles, quite like in Thai.

Are they an innovation in Thai [...]

Not necessarily. Off the top of my head, take the English word sir. It used to have the meaning of "title of honor of a knight or baronet" (link), but later became a respectful form of address or salutation.

Answer 2

Another word widely heard in Laos when they want to make a sentence more polite, I hear "ໂດຍ" or "ໂດຍຂ້ານ້ອຍ". After asking some friends who speak Lao as a mothertongue, they always use "ໂດย", the shorten form of "ໂດຍຂ້ານ້ອຍ" which is older and more polite, with people in general but prefer using "ເຈົ້າ" with people in higher age and rank, additionally for official use.