I believe it was in 1984, maybe 1985 when the RV industry was required to supply seat belts for every "official" seating position inside all motor homes. If you bought a used rig without seat belts, most likely the previous owner removed them. All PC dinettes, couches, and fixed individual seats have seat belts.
Regarding the later day Euro chair in many newer PCs including model 2350, it is not an "official" seating position. It is not attached to the motor home for use when the rig is in motion. It has a simple storing clamp to prevent it from moving around while the rig is driven. Therefore it does not have seat belts. If considering any PC with a Euro chair, you will have to replace it with a fixed chair typically mounted on a pedestal, bolted through the floor of the motor home. If ordering a new PC, just ask the factory to do that for you, I believe at no extra charge. I do not recommend the low back chair called a barrel chair. Our rig originally came with that one but I replaced it with a 3rd matching captain seat for improved comfort and safety for a 3rd passenger along with great comfort when parked. The low back barrel chair is not good for relaxing.
Here are pictures of our 3rd occupant captain seat with seat belts. The pedestal it mounts to swivels and slides out from the center.
In this orientation I often slide the seat forward, (away from the wall) recline and use the dinette bench seat cushion as an ottoman.
My wife demonstrating one of many positions, here to watch a movie in comfort.
When sliding the seat in this position but into the isle, that passenger can look out the front window much better. Their feet end up in between the two front seats.
For reference, here is a Euro chair. Note the base is a metal ring that is not attached to the floor.
This seat is NOT to be used when driving.
