New rules in the USA make it ILLEGAL to operate ANY sort of drone flown out of sight of the operator. If you can't SEE it, it's ILLEGAL to FLY it. Also, ANY drone that weighs more than 0.55 lbs MUST be registered with the FAA, and if you want to operate a drone for commercial purposes, you need an operator's license.

I expect similar rules to be established in other countries soon.

It's a combination of engines, aerodynamics and altitude.

First, a jet can not fly faster than the velocity of the output of the engine. All commercial airliners use turbofan engines for fuel efficiency. These produce a huge amount of thrust by moving a large amount of air, but they move it at much lower speed than a pure turbojet.
Supersonic aircraft user afterburners - they dump extra fuel into the exhaust, where it burns much like a rocket engine would. That produces a very high speed flow, but it uses a huge amount of fuel. Some fighters are capable of "super cruise" - they use afterburners to get above Mach 1, but can cruise above Mach1 without

As you approach Mach 1, shockwaves begin to form- instead of flowing smoothly past the plane, air begins to compress into a wave, much like the bow wave on a boat. The aerodynamics of plane has to be designed to handle this - the shock waves change the behavior of the airflow. The engines need to have an inlet designed to manage the shockwave forming in the inlet, the control surfaces must be able to handle the changing aerodynamic balance without being effected by the shockwave themselves.
The greatest increase in drag is when the plane is "transonic". That means the plane is close to Mach1, but parts of the local airflow in some areas is already supersonic and forming a shockwave. There are several aerodynamic "tricks" that help minimize drag when going transonic - sharply swept or delta wings, and use of the "area rule" which means keeping the frontal area consistent. That's why some fighter jets had sections of the fuselage that would narrow right above the wings. They reduce the fuselage cross section where the wings had the greatest cross section.

And supersonic aircraft do tend to fly higher, where the air is thinner. "Efficient" is not the word you are looking for - that would mean they use less power for for each psi of pressurization. Since a plane at higher altitude must have a greater pressure differential, you could say the pressurization is more effective

Do you think that flying a fighter is just "G loads"...?
All Air Force and Navy pilots train for high "G" -
But there are thousands of other things with flying airplanes -

I trained in T-37 and T-38 with the Air Force, yet a pilot flying KC-135 tankers -
You get trained for the type of airplane you fly -
The F-16 is not the only airplane type in the Air Force -

I probably would have NO CLUE as to flying a F-35 -

Most airline pilots only fly one type of airplane (in their job) -
I could fly types I used to fly - but would need a few days for a refresher course -

Embarrassed...?
Why...?

I fail to understand your question -
Delta Airlines and Delta Connection are separate companies -
And so is United and United Express, or American Airlines and American Eagle -

They sometimes deadhead and ask for a jump seat... which they often get -
Last time I worked in USA was 1991 and it was ok then - I do not think it is any different today -
With Pan Am, we also had a commuter carrier - That was Ransome Airlines -

Aren't you embarrassed to be Anonymous and have a Blue Face...?

Only if Australia has a shortage of pilots. Which isn't going to happen any time soon.

If you wish to work in Australia then you have to be able to offer their economy a skill or talent which the Australian Visa Bureau has published on the current Skilled Occupation List.

Only if Australia has a shortage of pilots. Which isn't going to happen any time soon.

If you wish to work in Australia then you have to be able to offer their economy a skill or talent which the Australian Visa Bureau has published on the current Skilled Occupation List.