The amount of fuel a launcher burns to reach orbit is about the same as an airliner burns to go from North America to Ausralia. Largely they are due to different solutions to the same problems. Throw away hardware. Even the 'reusable' Space Shuttle throws away most of its weight in the form of an expendable external tank and salvageable solid rocket motors. This is the single biggest factor in making access to space expensive.
Airlines use reusable hardware and fly their aircraft several times every day.
This allows them to amortize the cost of the aircraft over literally thousands of passenger flights. The entire Shuttle fleet flies only eight times a year, while many airliners fly more than eight times per day. Redundant Hardware and Checks. This is well beyond the point of diminishing returns and sometimes results in greater harm. For example, a couple of years ago a Shuttle Orbiter was almost damaged when it was rotated from horizontal to vertical with a loose work-platform support still in its engine compartment.