Very interesting point! I do mark these as "equally wrong." They both get zero credit. But if a student wrote "b-f-g," I'd be concerned. Perhaps in reality, they're both wrong, but one deserves more critical attention than the other.

I had too many experiences as a students writing down long workings, marking down my thought processes clearly only to find that I get a big fat zero in the end. The answer is wrong despite having the "correct" thought process.

I'm teaching maths now. I make it a habit to ask my students how they got they're answers regardless if they got the answer right or not.