Years ago, we had a huge space connected to our shop that just collected junk and cost us money. We rented it out to these guys who did auto repairs. They were from St. Vincent in the Caribbean so for some religious reason, they didn't work on Saturdays. Almost EVERY Saturday, someone would pull up and knock on our door looking for them. It was always some customer who had their car fixed by them on the day or two before and there was some problem. Usually, a slight leak that we would just tighten or we would tell them it needed further attention and get it back to them tomorrow when they open.
The best one ever was this young guy came in, asked if we knew when they were open again and I smelled gas... BAD. I said open your hood. He opens it and his fuel regulator was spewing gasoline profusely where it pressed onto the fuel rail. I told the kid you can't drive like that. He said I need to, I have a date tonight. I felt bad for him so, being a diesel shop, we had quite the collection of O rings. We found one that fit the regulator and fixed him up. We also suggested he find a different repair shop.
I don't think these guys didn't care but I do think they were used to cutting corners to save a buck since maybe they were used to not being able to obtain parts easily.
MAYBE the guys that did that head gasket were trying to do it on the bare minimum as per her orders.