A court of law saying, "It is simpler, easier, and more beneficial to consumers that laws written for 'sandwiches' apply to hot dogs" is, itself, a utility argument. It's not about simplicity of description, it's about simplicity of regulation. No need to redouble effort when the same safety and food-purity laws apply cleanly to both things.
Exactly.
To the average speaker, a hot dog is not a sandwich; if you refer to a hot dog as "that sandwich," e.g. by saying, "can you please hand me that sandwich," most fluent English speakers would get at least mildly confused. Most would ask you to clarify: "Did you mean this hot dog?" This implies people get that hot dogs and sandwiches are similar/related, but not so much that they're totally interchangeable in all circumstances.
To a judge, civil servant, legislator, or lawyer? The similarities far outweigh the differences. But this can be true even if things are completely NOT the same, or are things most people would definitely reject as being called "sandwiches," such as tacos (which, yes, there is a legal precedent out there somewhere that tacos are classifiable as "sandwiches".)
Finally, both your metric and mine reject the idea that coffee is a soup. It is a steeped and brewed beverage.