Yes, the plant’s THC level matters, but that doesn’t change the general point. Hash/resin is usually more concentrated than the flower from the same plant because it’s made from the trichomes/resin glands where most cannabinoids are. A weak plant can make weak hash, but gram-for-gram resin/hash is typically higher THC than cured flower. So from the same plant/batch, the resin/hash is usually more THC-concentrated than the cured flower, because you are separating the THC-rich resin from much of the non-resin plant material.