Not only is "arguments are evaluated left-to-right" less easy to formalize than you think, it would also make all C code run slower, because the compiler would no longer be able to interleave computations for more efficient pipelining. The same goes for "expression is [only evaluated once]/[always evaluated twice]".

Of course the developer is navigating a minefield every time they use volatile, that's why it's called "volatile" - an English word otherwise only commonly used in chemistry, where it means "stuff that wants to go boom".

Your argument makes no sense since the developer is expected to perform manual sequencing. Correctly written UB free code cannot be interleaved either.

All you've achieved is that the standard C function call syntax can no longer be used as is.