Going by the info in those downloads, it seems the rules have not changed for Cambodian ("local") registered vehicles entering Thailand.
"Local vehicle" means vehicles and motorcycles, registered in any country sharing a common border with Thailand, that regularly enter or exit Thailand via a border Customs House for business purposes such as to purchase consumption goods, to seek medical treatment and education and so on. A local vehicle must travel inside the Kingdom only within the prescribed areas and must observe the criteria stipulated by the Department of Land Transport........
.....The notification shall not apply to the following types of vehicles:
(1) Vehicles imported under the cooperation between the Thai government and the government of that country.
(2) Vehicles of the country with existing agreement on land transportation with Thailand such as the Federation of Malaysia, the Republic of Singapore, and Lao PDR.
(3) Local vehicles.
and from the summary
Exempted from this regulation:
- Vehicle used for Thai-Foreign Government Collaboration
- Locally frequent vehicles under local customs jurisdiction
- Vehicles registered in Lao, Malaysia and Singapore
I guess it was always the case that Cambodian vehicles entering Thailand were officially restricted to the province of entry/local customs jurisdiction. However, in practice, that restriction was rarely enforced and we could go wherever we liked.
Question is, how strictly will it be enforced from now ?
Still not enforced much. However, they most likely need to return through the same border customs house as they entered, which is the same regulation that applies to Thai vehicles entering Cambodia, even though that's not enforced much either.
Last week I saw 1 Cambodian SUV driving towards Chonburi/Bangkok in Ban Beung, Chonburi province.
Another Cambodian Hilux VIGO was driving along the coastal scenic road in Chantaburi province. If this vehicle was allowed to enter via one of the Chantaburi crossings (most likely Ban Pakkard as Ban Laem generally doesn't allow vehicles across further than the market) then it didn't break the rules. However, if it came from Koh Kong, then it did.
Saw a couple of Cambodian vehicles in Trat city (this is allowed anyway). Also saw a Cambodian 100cc scooter heading towards Trat (also allowed under both the old and new regulations).
Back in December, saw a Cambodian motorcycle (big bike) driving north between Mae Sot and Mae Sariang, together with a Thai big bike. Didn't see the rider, but suspect it was an expat based in Cambodia. Maybe he had a permit, though probably he didn't.
When Cambodia finally signs an agreement with Thailand covering private vehicles, this ambiguity should end. In the meantime, it's a huge pain getting a Thai vehicle into Cambodia anywhere other than at Ban Had Lek/Koh Kong and Chong Chom/O'Smach. Yet my understanding is that Cambodian vehicles have been allowed to enter Thailand at Aranyaprathet (opposite Poipet) and then proceeded from there to Bangkok (now they are probably being told, can't leave Sa Kaew). In the other direction, it was nearly impossible without doing a runner or getting a permit. That's plain unfair. More reciprocity is needed and I hope Cambodia will now be pressured into allowing Thai vehicles in freely at every border checkpoint (and for that matter, Lao and Vietnamese vehicles across their respective borders)-Vietnam and Laos have also complained about how they let in the Cambodians freely but in the reverse direction it's not as easy for their vehicles to enter.