I got this suggestion from a thread on the Lilies forum, where people who have both cats and lilies deny there is a high risk of death despite the overwhelming contrary evidence in scientific studies. Obviously I will never believe it, but this is an interesting idea. Here is the topic:

It is likely that cats inherently just "know" not to eat lilies. Similar to poisonous caterpillars with certain vivid markings: somehow the predators just "know" not to eat them. The empirical facts are there that document a poison in lilies (listed in my first post). But no need to get uppity about it. Gosh, if we tried to keep all poisonous things away from pets, it would be more than a full time job!
Some cats also are not attracted to plant material. They've apparently done studies on this, read about it a couple years ago. Here I have plant munchers. One of my cats bit into a lily leaf, but did not take any material out. I was thankful, but maybe Lefty's theory prevails here. He knows it tastes like death and took off without ingesting any.
I agree with @Leftwood ... "It is likely that cats inherently just "know" not to eat lilies." I think all animals avoid plant foods that are poisonous to them instinctively. Of course, some animals are smarter than others, but that's the same with humans.

The thread got off topic for a while, so I don't recommend reading many other posts in it. I am just throwing it out here to see what other people think.