Just like any other 50 year old vehicle, they've all lived different lives, condition of some are better than others no matter the market. Anyone looking at a vehicle this old needs to do their due diligence and educate themselves prior to buying anything.
A lot of the SA trucks I've seen have been poorly restored. Not all, but many of them have been thrown together with cheap labor, a fresh coat of paint, and odd ball parts to get it running and driving. It is then imported to the US where they hope for big profits from American buyers who are distracted by shiny paint. You can see a lot of this "workmanship" on past BaT auction photos once you start looking at the close up pictures.
That said, I am not against SA trucks (I own one). I feel like it has been done right and it was restored south of the border. I flew out to look at it in person and educated myself for months before buying. It is very straight and dry underneath, which is not surprising given the dry climate down there. I felt comfortable with the truck so I went for it. Mud was a great resource.
Keep in mind the SA trucks do not have emissions equipment on them, and I don't think it can be retrofitted either. That may be important to some buyers who have to pass emissions. Other differences I see mentioned on Mud are lack of dash pad, heater, roll bar, and disc brakes. Transmissions are different too I think, H41 vs H42.
One thing I've dealt with owning an SA FJ40 is some of the parts are different than US spec. So you won't be able to find some things from the dealer. My mechanic told me his parts guy couldn't recognize my VIN. There are other sources that have been great at getting me Non US parts like sor.com. Another good resource to look up part numbers and drawings for Non US trucks are sites like
Parts catalog for Toyota Land Cruiser - https://toyota-general.epc-data.com/land_cruiser/ and
ToyoDIY.com - https://www.toyodiy.com/parts/
I guess what I'm getting at is to not dismiss a truck just because it is SA or non US. There were differences to be aware of so just know what you are buying and research before committing to anything