That’s unusual for someone at the dealership to state that all 4 are leaking.
Over time it is possible for a slight oil film to develop around the struts or shocks. With a little dust residue it may appear to be worse than it actuall is.
Some car makers (Subaru for one) even states that this can be considered “normal”.
Since the expertise of techs can vary a lot I wonder if you just happened to run across a crook or a younger guy who may honestly think they’re all bad?
I’m not saying that all 4 are good here; only that it sounds very suspect. Since it’s suspect another opinion should be gotten.
It is possible to have a bit of discoloration in the trans and power steering fluid and my opinion is that the transmission fluid especially should be changed; preferably at 30k mile intervals. It’s cheap insurance.