It's very naive but worth looking into. Could always test this if it is really costing so much money for one word. Or build another smaller model that detects if it is part of the important content or not.
There are hundreds of other opportunities for cost savings and efficiency gains that don’t have a visible UX impact. The trade-off just isn’t worth it outside of some very specialized scenarios where the user is sophisticated enough to deliberately omit the word anyway.
They would write “How do you say ‘yes please’ in French”. Or “translate yes please in French”.
To think that a model wouldn’t be capable of knowing this instance of please is important but can code for us is crazy.
Or you could just not bother with dealing with this special case that isn't actually that expensive.