Usually if you look in the owner’s manual you will see the maintenance recommendations based on mileage at 30000 mi, rear differential, front differential, and transfer case fluid should be replaced. On some of the vehicles. It actually says to do it every 15,000 miles. I understand it may feel like a rip-off, but if Toyota makes the recommendation in their owner’s manual to change that fluid then I don’t think the dealer is at fault.
Just looked up a 2020 AWD RAV4. For 15k they say “Inspect transfer oil” this is for normal maintenance, but a little lower in the 15k explanation they say, “if towing, car-top carrier, or heavy loading replace transfer oil and rear diff oil.”
Now at the 30k, they just explicitly say replace transfer case oil for all conditions.
Mind you this is RAV4 gasoline engine. The Hybrid has other interesting maintenance items, such as clean HV filter every 5000 miles