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Having worked in commercial as a general builder (at Heathrow where the H&S culture is off the scale) artex isn't considered a risk there even. Artex is, from memory, 1-2% azzy we did one job where we refurbed a bunch of airside offices. These offices were forgotten about at some point in the late 70s and were like a time capsule (a stash of hairy 70s jazz mags were found in a desk drawer even). The walls and ceiling were covered in artex that was surveyed and found to contain asbestos. The asbestos removal experts provided us with RAMS, told us what products and processes to use, set up air quality monitoring and let us get on with it as the risk was perceived to be so low.
It's often like this with trades especially domestic work. We've all arrived at working methods based on the prevailing conditions, including price. There's always a trade off.
Quote for testing and you lose the work to people who say it's not necessary. Maybe you move to commercial where testing would be mandatory, perhaps you let it slide because most of the time there's no risk. Follow this to it's conclusion and you see why there's a lot of bad decision making in domestic maintenance.
Obviously testing could reveal an undesirable answer so the smart thing to do is test it independently and then instruct the plasterer based on the results. Google asbestos testing kit to see what's involved.