Nope. Not unless there is reason to believe something is wrong. Was it running rough at the time? Did you tell them it was running rough?
The mechanic was told “replace the cat.” So that’s what he did. He would have had no reason to inspect the entire engine to see if anything could possibly be wrong that would hurt the cat, because they weren’t replacing the cat due to a premature failure that would indicate something wrong upstream, but due to a recall.
I don’t have to. I understand that women face discrimination. However, the person who worked on your car probably didn’t even know you are a woman. That person is not the same person that you dealt with. The person who worked on your car saw a car, saw the work sheet telling them what to do to the car, and did it. It is almost a certainty that you were not discriminated against by the person who worked on your car because even if that person is the type of idiot who discriminates against women, they would have to know that you were a woman first in order to discriminate against you.
That’s true, but there’s a caveat. Subaru will give them a certain amount to do the job, no matter how long it actually takes to do the job. So if Subaru decides the job takes one hour, but the job actually takes 2, then the dealership has to eat that second hour. So, they get paid, but they often do not get paid as much as they should be – not that this is a reason for them to slack off on the job, but it’s certainly a reason not to go fishing around for problems that they have no indication exist - that would be extra unpaid time that they’d have to eat, and it is not reasonable to expect them to eat it.
There’s one possible avenue you could take to get some financial relief here - do you still have the paperwork from the bad spark plug replacement job? If you do, you could approach them, tell them the wrong plugs were installed, you believe that caused the premature failure of the cat, and you want them to make it right.
They may tell you to pound sand, at which point you get to decide if you want to let it go or sue them, but they may also be a reputable shop that made an honest mistake and will try to make it right.