Taylor Ham, Egg & Cheese is the official breakfast sandwich of New Jersey. As in your example, ketchup is the default condiment and that fact disgusts me as well, as it should disgust any human four years of age or older.

Now no one would consider putting ketchup on a plain Taylor Ham sandwich any more than one would squirt ketchup atop a couldcut ham sandwich--mustard would be the obvious choice of a grown-up.

Therefore, when I order a Taylor Ham, Egg & Cheese for personal consumption I request mustard, an admittedly bold choice given that mustard and eggs are not commonly paired, but mustard is the logical condiment. The acidic tang of a thin spread of deli mustard adds complexity and deliciousness whereas globbing a gaudy admixture of high fructose corn syrup and stewed tomato smothers said sandwich in a sickening slurry of sweetness.

Why then is ketchup all but de rigueur on a Taylor Ham, Egg & Cheese? That I can not answer. Perhaps someone here can explain?