I talked to the DPS and this is what I found out.
This is not a new law. Trailers have always required yearly inspections, but a recent enforcement campaign has begun. (Probably to generate revenue for the state)
If the total unloaded weight of the trailer is over 4500 lbs it is required to be inspected.
The inspection covers all types of trailers, bumper pull, goose neck, enclosed, travel trailers, etc…
The number of axels does not matter, it goes by weight.
Brakes on the all inspected trailers are required.
If manufactured after a certain date (which the guy did not know off the top of his head) an operational break away brake is required. Or if the trailer was originally equipped with the break away brake, it must be functional.
And mud flaps are required on the rear axle.
I called my local Kwik Kar oil change place and they said they did trailer inspections. I asked what all they checked and he said: “We check tires and lights” I said, “Do you check the trailer brakes” He said “No, its not required” I told the guy at the DPS what the Kwik Kar said and he said that was typical. Most places don’t properly inspect the trailers, but even with the valid inspection sticker they can still ticket you for not having functional equipment on the trailer.