>>14392850If we are to assume that plants do feel pain then further assumptions can safely be made, for example, eating tomatoes, apples, any flowering fruit or veg which is in the plants best interest to be eaten will likely not cause pain. You can use this framework to look deeper into the comparison of eating cows and vegan diets, for example some of the plants which experience pain may be a staple of vegan diets while cows for the most part are just eating grass - which for all we know doesn't experience pain. In this scenario vegans would be causing pain and suffering orders of magnitude higher than someone who kills and eats cows.
Also as a side-note, the plant matter fed to pigs, cows before slaughter to fatten them, chickens, etc, is often unusable byproducts of the biofuel industry (such as onions husks), and any 'pain' the plants may have experienced would happen long before an animal is anywhere near the plants