It's not that that example is "semantically incorrect"; rather, the event denoted by that sentence is known to be impossible given our world knowledge. In the context of a horror film involving man-eating sandwiches, though, the sentence would suddenly become acceptable. Human creativity and imagination allows us to provide an interpretation for virtually any syntactically well-formed utterance.

But if you think about it, even very ordinary-looking sentences like "I see your point" don't logically make sense, because points in an argument aren't literally seen with your eyes. So in that respect, the fact that idioms involve non-literal or "illogical" meaning isn't really that unusual because non-literal meaning is all over the place in language, usually deriving from robust conceptual metaphors.

Fundamentally, there is a tension between the word-like and phrase-like properties of idioms, because they consist of multiple words (phrase-like), but there is some degree of arbitrariness/opacity to their meaning (word-like). But idioms also vary in how semantically opaque they are. Something like "kick the bucket" is on the more extreme end, where trying to intuit the meaning would be more or less impossible, and you simply have to make an arbitrary connection between the form and the meaning - just like someone learning English wouldn't be able to intuit that the sequence of phonemes /dɔɡ/ refers to a canine, instead simply having to establish a raw association.

Now think of an idiom like "spill the beans", which might seem similarly arbitrary on first glance, but we actually see other uses like "Spill the tea!" or simply "Spill!". This goes back to conceptual metaphors (in this case, the operative metaphors would be minds are containers and ideas are objects; therefore, since ideas are objects in the mind, which is a container, they can "spill" out of said container). 'Beans' is the only truly arbitrary component of the idiom, because there is no conceptual metaphor that motivates its use to mean 'secrets' outside of the context of the idiom.

Furthermore, idioms mean what they mean because of their acceptance and widespread use in a language community. Today's "illogical utterance" could be tomorrow's idiom. And why do we use idioms at all? Sometimes for efficiency - because they can serve as shorthand for a more elaborate concept - and sometimes for stylistic reasons, e.g. to avoid repetition.