This is not 80% for one theatre chain, it's for three chains.
Big theatres are a substantial capital investment, modern digital projectors are also not cheap. The set of businesses interested in running a theatre chain and financially able to do so is not large. There are also some economies of scale..
Your post is illogical. "Color of their skin" is something a hotelier can see, "the sexual acts they may or may not partake of" are pure speculation. FWIW, a hotelier can take steps to prevent his property from being trashed.
Similarly, "the content of their character" is pure speculation unless they announce their intentions (something that only fools and troublemakers are likely to do.)
"The content of the ads" is a business decision; they don't want to display material that could discourage customers from returning. Content is part of the service they're providing, and they're providing it to anyone who'll pay for it. This is different from your proposed hotelier, who would not be providing service to anyone who'd pay for it.
"Freedom of expression" is far too broad. It would include things like a man removing his clothes and masturbating in front of a group of nuns and small children.
The primary purpose of freedom of press and speech is to protect a mechanism for limiting government power and abuse. It is the freedom to transmit ideas. Freedom of expression covers a much wider range of activity, too much of which is undeserving of protection.
People with legal access to government secrets sign an agreement acknowledging that they understand and will abide by the laws relevant to those secrets. There are also laws concerning acquiring secrets one is not permitted to acquire.
Additionally, "free speech" is absence of prior constraint, not absence of repercussions for damage. That covers the theoretical problem.
On a practical basis, get real. Passing nuclear secrets is attempted murder and an act of war.
No. A TWT relies on the velocity of electrons inside the tube and bunches up the electrons. At least a full cycle of the signal has to be present inside the tube at once. If the velocity is about c/10 (I'm guessing this is a reasonable low end) the tube would have to be 150 meters long for a 200 kHz signal.Precision machining is required, so TWTs are expensive.
Metal detectors operate at frequencies where semiconductors can be extremely efficient -- I'm guessing better than 90% using PWM and LC filtering. There's not much utility in trying for more.
The rights of children are not the same as the rights of adults. The parents' responsibility for their children gives them special proper powers over their children, a subset of which, in loco parentis, are temporarily extended to schools.
Using their best judgement, parents may spank their children to prevent them from running in front of cars or kicking the neighbor's pitbull. This is not a violation of a child's rights.
Mommy, what happens to your files when you die?