[mrguyorama]

Kinetic energy of an airplane: 40 kilojoules per kilogram at high cruising speed

Kinetic energy of a rocket: 30 megajoules per kilogram at low earth orbit

It's the difference between one C sized alkaline battery, and slightly under one kilogram of gasoline perfectly mixed with oxygen and ignited in an explosion.

That order of magnitude difference in energy is the difficulty. Fundamentally, an airliner is a dramatically easier engineering task than an orbital capable rocket.

The universe's entire shtick is being very very unwelcoming to high energies, and has a strong tendency to take anything that is a high concentration of energy and turn it into a very spread out glob of much lower energy, or even into an entirely new form of something that "has" less energy but is way less useful to us.