It is allowed to used an encrypted connection to administer a remote repeater, like for amateur satellites. Only the control link may be encrypted. The repeated signals may not, just like any other amateur transmissions.
Radio spectrum is a limited and shared resource. It makes sense that it's licensed and regulated. But compared to other parts of the spectrum, the license is cheap and easy to get and the regulations are minimal. It's a public space for experimentation. If you don't want to be seen in public, go to some other area of the spectrum.
That's not hard to imagine. Quick, what's 1/3 of a meter? The sometimes problem with metric is it's base-10. The prime factors of 10 are 2 and 5. Feet are in base-12, which has the prime factors 2 and 3. Three is much more useful than five. There are marks on your measuring tape at exactly 1/3 of a yard or 1/3 of a foot.
Metric is often easier and more convenient, but not always. So, in the US, we tend to use metric or customary units depending on which is more convenient for the task at hand. Actually, it's a lot like the UK and other countries where older systems still exist alongside metric. The difference with the US is that we don't have as many unnecessary laws mandating metric. You're an adult. You're working with other adults. You're perfectly capable of figuring out what to do without the input of lifelong politicians who've never measured a thing in their lives. Except for the amount of your money that they're going to spend. They like measuring that.