"You think she’s being difficult because she hears you shout chicken, but not her name. Think of it as, she’s totally absorbed in what she’s doing- sunbathing, sniffing, wondering who’s around the corner, not really paying attention to anything else that’s going on, when suddenly someone shouts sausages! Sausages are even more interesting than the sniffs. She’s going to check it out. It’s like tuning out background noise on public transport, but looking up when your stop is mentioned."
That's a really great description, am going to remember that with my boy sometimes! I think for the OP it could also be that the dogs old and tired, coming for her name is too much effort, but for chicken (or sausages), the dog will make that effort. It could also be that the dog isn't getting out as much so is more reluctant to come back when they know that's the end of fun time.
But whatever the cause, OP your dog is not doing any of this to spite you, dogs don't think like that. The way you talk about your dog comes across as quite cold and uncaring (although I appreciate that it's hard to deal with accidents in the house).
I think you need to take your dog to the vets to rule out any medical issues that is causing the toileting inside. But as your dog is elderly and having toileting issues I'd also have a chat with the vet re quality of life and whether it is time to pts.