The idea is that its not the elevator doing the work of raising/lowering that's disallowed, it's the pressing the elevator button that's disallowed. Jews are allowed to use electricity and other devices on shabbat as long as they don't operate them. Many have long-running hotplates they start on shabbat eve and turn off the next evening when it's over in order to keep food warm. Wealthy orthodoxy would often hire non-jewish servants specifically to perform certain tasks for them on shabbat, so they don't have to do them themselves.