Airplane speed traps are completely based on convictions solely on the word of a cop

That's not true, Airplane "speed traps" use a device called VASCAR which is basically a visual radar/recorder which specifically calculates the speed of objects moving below on the ground, additionally, such speed traps almost always work in conjunction with an officer on the ground - the pilot will radio the ground-officer when someone is detected speeding. I researched this in depth some months ago when doing a lot of driving through Virginia, where the the "speed limit enforced by aircraft signs" are all up and down the interstate.

and for many, many years, cops would "clock" you by driving a steady distance between your car and his to get a reliable enough evidence of speed to give an enforceable ticket.

Not sure why you say that contradicts my point, because that just reinforces the point I was making. That example is valid because they almost always have a camera on the front of the car. They don't need a radar if they are matching your speed and it is being recorded on video. That serves as evidence of how fast you were going, making the officers testimony irrelevant.

If you go into a court room, and tell the judge you want to be tried on the ticket, the judge is going to throw the case out if there is no actual evidence other than a single officers testimony. I've even seen cases get thrown out even when there was 2 officers testimony, but strictly nothing else. You can't tell me it doesn't happen. I've been in the court room before and watched it happen. It is a false idea that people get convictions off mere testimony, unless you're talking multiple very strong independent witnesses. Usually people who claim "conviction by lone testimony" are deliberately leaving out other relevant factors, such as whether the person took a voluntary plea, or other evidence they "forgot to mention".