This is merely an implementation tradeoff: I could trivially modify a compiler to support exceptions that were as fast as returning error sum types without any

This is merely an implementation tradeoff: I could trivially modify a compiler to support exceptions that were as fast as returning error sum types without any syntax changes, but it comes at the cost of making all non-failing code slower--as you have to litter the runtime with checks that exceptions elide--so we don't generally do it... but like, if you make a new language and don't go with the syntax of exceptions because you like the implementation of sum types, I feel you have misunderstood the problem space. (As for "handling" errors, you should only have a few places in the entire codebase which do that... littering the entire codebase with opportunities to feel like you might could handle an error seems like a mistake as it just encourages more handling.)