Hey, finally a topic I can contribute something to (I dabble in making my own olive oil).

Depending on what you mean by chemical methods, you might not be 100% correct. The vast majority of food grade olive oil (including really high quality stuff) is extracted by crushing the olives into a mash, mixing it with warm water and spinning the resulting paste in a centrifuge. The quality varies according to the quality of the fruit, when it’s picked, how much oil you’re trying to squeeze out, and the variables you control are basically the quality and quantity of water in the mash. It’s classified as virgin or extra virgin according to the chemical composition, and the “cold pressed” is more of a marketing term than an actual process. It’s nowadays supposed to mean that the mash doesn’t get over a certain temperature in the extraction, but if it did it would be poor quality oil anyway, so it’s pretty meaningless for “decent or above” oil quality. Purely mechanically pressed oil is exceedingly rare and has a more muted flavor because it skips the process of mixing the mash with water, which activates the aromatic compounds.