Your "over all the years" experience isn't even a drop in a bucket in the grand scheme. Most of the snakes you listed would eat a scented stone if you threw it at them so that doesn't much help either.
Let's go hypothetical and say that I decided to agree with you that every snake can eventually be coaxed to willingly feed on f/t prey. How long can we ethically wait before resorting to assist feeding? Why don't you feel obligated to exhaust all methods of food presentation, including live, as a responsible owner who has decided to keep these animals? You're keeping snakes as pets - for the most part, animals that don't slither around scavenging meals. Sure, some species will jump on f/t right out of the gate, but not all. Is this really a more ethical solution than feeding a live rodent? What about for the snake? Shouldn't they be offered the courtesy of a full stomach without us starving them out first or heaping stress on them by shoving something, unwanted, into their gullet?