Equivalent implicit operators: why are they legal?

Question

Update!

See my dissection of a portion of the C# spec below; I think I must be missing something, because to me it looks like the behavior I\'

Answer 1

Ultimately, it can't be prohibitted with complete success. You and I could publish two assemblies. They we could start using each other's assembles, while updating our own. Then we could each provide implicit casts between types defined in each assembly. Only when we release the next version, could this be caught, rather than at compile time.

There's an advantage in not trying to ban things that can't be banned, as it makes for clarity and consistency (and there's a lesson for legislators in that).