Why is the launch of the shuttle delayed because of bad weather, when commercial airliners take off and land in thunderstorms and lightning?
The shuttle is quite different from a commercial airliner. The shuttle launches straight up through any clouds that are there. Airliners sometimes fly through clouds, but they can avoid the worst ones. Rocket exhaust plumes stretching from the shuttle (or other rockets) to the ground makes an excellent lightning rod and therefore lightning is drawn especially to a flying rocket. This is very dangerous. The shuttle has a fragile and critical thermal tile skin that must be intact for re-entry. Lightning strikes would probably shatter thermal tiles. The shuttle also uses extremely explosive hydrogen and oxygen for fuel. A lightning strike on or near the launch pad or during flight could cause this propellant to explode. An airliner uses a kerosene-like fuel which is far less flammable. Airliners can land in the rain, but even they often delay or divert to avoid severe thunderstorms.
