Every vehicle on the road has specific requirements for which fluids meet required specs and any competent shop will check to ensure the fluid meets spec before draining/filling. They have books with every make/model/year listing the proper fluids.
That said, shops are run by humans and humans take shortcuts. When a dealership makes a mistake, they are liable. When a third-party oil change shop makes the mistake, they are liable. When an owner makes the mistake, they are liable. The warranty isn't completely voided, it's just that the manufacture isn't liable for other's mistakes. This is not scary as long as you are dealing with reputable shops. I had a Ford dealer fill my 1 year old F-150 with a 4.6L V8 with one quart too much oil because they didn't look up the proper fill amount. They filled it as if it were a 5.4L V8. Yes, this can cause damage to seals, oxygen sensors, and greatly reduce MPG. But they took care of it. Ford had nothing to do with it as Ford Dealerships are independent shops.
But it's not odd that different vehicles require different fluids. It would be odd to assume they should all be the same. That's why there is such a thing as specifications for each vehicle. So it's not scary to have an independent shop work on your Rivian as long as they are qualified and can read instructions.
I thought Rivian is planning a mobile service network like Tesla has. This will be the best solution for those who don't live near a Rivian Service Center. The world is developing new, more efficient, more cost effective ways to achieve the same thing.