I'm A Great Cool

The reason that flight times can be so different is mainly dependent on three things: the specific aircraft, the route, and the wind. I could go on tangents about all of these, but the point is that you can be flying the exact same plane on the exact same route at the exact same airspeed… and still get drastically different travel times due to the wind fucking with your ground speed.

(Ground speed = true air speed + wind component, if you care.)

And if you’re worried about pilots ramping that shit up to the maximum velocity… you would know if we did. Because we would have to point the nose down for the whole flight. The engines are already often operating at their maximum thrust any time you’re departing or ascending— but as my flight instructors have screamed at me since the day I started flying, “pitch for speed, power for altitude”. I’m not even sure you can hit the “never-exceed” velocities in a stable airplane without slamming the stick forward and nosediving that thang.

We also have this handy color coding on the air speed indicator! (And similar coding on the vertical tape versions in those newfangled glass cockpits.)

Lastly, almost every commercial flight is going to have two people up front. Even if the captain does something stupid, the first officer is there to say “hey, don’t do that” and make corrections accordingly. Even if they do agree to do something dumb, someone on the ground is going to tell them to cut it out. Nobody just gets to fuck around up there.