I’ve never dined at Royal, but Wawa and Sheetz, while certainly borderline edible, are blown out of the water by local convienence stores. Many of which, in my area, are located in former non-gas-station Wawas, offer decent quality deli meats (Boars Head, Thumans, Dietz & Watson), excellent wide selections of coffees, and give you context for how laughably overpriced Wawa, in particular, is. You can usually get excellent cheesesteaks, although to be honest I can swing a cat in my neighborhood and hit five such places.
That being said, my memory of AmCafe food is that it like Wawa et al, is borderline edible and provides a reasonable alternative to ancient packed food or risking missing the train by rushing to shop off of it.
I think the real argument is what defines “good” to someone, which is highly subjective and individual. I’ve been asked by some food vendors what I think constitutes good coffee when I tell my wife I think theirs is passable and my response is the truth: you make coffee of the strength and flavor profile I consider good, and I will likely be your only customer.
A train cafe has to cater to a large swath of the American public who has different ideas of what good is; you try serving what the average New Jerseyan, all of whom are honorary Italian-Americans, think of as good pizza to somebody from rural central PA, and they will very likely find it way too spicy and practically inedible. (Real life test, btw.) pizza from that area is almost flavorless to me; once I got used to what you get at farmers markets in Berks/Lancaster, meats from where I grew up started tasting distinctly like paper.
Amtrak sort of has to provide a National menu that suits (or is at least tolerable to) the tastes of all of us. And we want them to meet dietary restrictions, too. I mean really, why do you think garbage pablum vendors like Applebees and Olive Garden have a foot hold?