So, my Mom just bought a bottle of Trader Joe's Expeller Pressed Canola Oil and it specifically says "no solvents". So I guess it may be possible to extract veggie oils without using solvents, but it's probably way quicker and cheaper to just squirt in a load of solvents?

Here's the ingredients list from their Canola Cooking Oil spray:
Trader Joe’s Canola Oil Cooking Spray is made from naturally clear expeller pressed canola oil. Canola Oil spray is excellent for non stick frying, sautéing or baking. It can be used for cooking meats, poultry, eggs and vegetables or to make garlic bread. It can also be lightly sprayed directly onto salad greens, hot pasta or vegetables to add flavor. Trader Joe’s Canola Oil Cooking Spray is a sodium and cholesterol free food and is made without alcohol.
I kind of see where you're coming from on the animal fats issue. The corn oil can definitely go...but the Aztecs did grind up peanut paste as one of their revered foods. So I ain't giving up my peanut butter yet.
I also like your perspective on being more careful about just picking up a 'natural' product from a health food store. You can't assume that it's not processed and treated with chemicals. It seems like some families are way more sensative than others to chemicals and even traditional and natural food sources. But even those of us who are not as sensative should take heed that the human gene pool can only take so much before our bodies begin to strain under the burden of even 'natural' food sources.
Animal fats are way easier to come by.* So if you believe that God created things for humans to eat, then it makes way more sense to eat easy to come by butter than heat-extracted-solvent-hardened-bleached-deoderized-corn oil. (I often wondered why corn isn't oily if they get oil out of it.)
So that's all fine and good for Adam and his descendants up until about 100 years ago. But, hey. I don't plan on hanging around forever in this flawed up earth suit anyway. Bring on New Heaven and New Earth!
*I remembered an important Biblical clue this morning: Man didn't eat animals until post-flood. Of course, they did have access to butter/milk. But some vegetable sources of fats must have been available and part of the diet for the first thousand years or so of human history. No doubt that the condition of plants was hugely altered post flood...and man needed to introduce meats into the diet. But God was good to preserve a portion of the power of plants, as can be seen in our lovely herbs. So plant fats can't be all that bad in their natural state. I guess I'll pay more attention to finding healthy plant based fats as close to their natural state as possible, and try to focus on using animal based fats for cooking.
Thanks for such a thought provoking topic, and all of your research and great info SC!