Let me give some figures for a 757-300..

For a Flap 5, 15 or 20 take off a 757-300 requires an attitude of 7.5 degrees to lift off the ground and will have a clearance between the underside of the tail and the runway of just 26 inches (66cm)! Bearing in mind that a tailstrike will occur at 9.5 degrees that leaves 2 degrees margin for error while trying to balance 120 tonnes on eight wheels at nearly 200mph. Suddenly doesn’t seem so difficult to hit the tail! On landing a body angle of 4 to 5 degrees is required however the tailstrike attitude is much lower as the the main gear struts compress.