High speed anything meets the Concorde problem - increasing cost for diminishing returns in trip time.
If it's using the air-hockey principle, I'd expect reduced forward pressure to below the limit on which the vehicle can float, so it starts to skid along the ground, hopefully with enough inter-car spacing that you don't get a pileup.
A less catastrophic situation might be, what happens if the pipe has a relatively minor leak due to subsidence or whatever? Just a loss of efficiency, or loss of function?
You may have a different opinion. It gets brought up because not all of the world shares your opinion.
Generally the TSA x-rays my bags looking for weapons and makes me walk through a metal detector, then I go on my way. Sometimes the line is 15-20 minutes, though usually it's less than 5. Sometimes there's a millimeter wave body scanner that some might find intrusive - personally I couldn't care less if a TSA employee sees my junk, and those that object can opt for a pat down. Those that object to being touched might be better served by a therapist than a plane ride.
This objection to flying because of the TSA is a psychological problem on your part and has nothing to do with reality. Unless you are carrying prohibited items - knives, liquids, etc - you will almost never encounter a problem with the TSA. Sure, the rule may be arbitrary and ridiculous, but they are not particularly onerous or oppressive either. I certainly make comments on bad policies and advocate for change. The system is nowhere close to the gestapo crazies seem to make it out to be.
Of course, you're likely psychotically obsessed so this will mean nothing to you, but get some help.
Your claim that they do not treat people as criminals because you don't mind or encounter trouble is laughable. Some of us don't have a case of Stockholm Syndrome to sooth the abuse.
Of course as someone who sympathizes with and advocates for your aggressors you won't understand where I am coming from, but get some help.
"I'm going to feel with my glove inside your waistband now..."
"It's rather clear you have no idea what criminals are treated like."
TSA have always treated me and everyone I know decently. Airport security is basically the same as it was 30 years ago. It's really disgusting and irresponsible to attack the TSA for carefully and respectfully enforcing regulations. I have no problem attacking idiotic regulations and regulators.
And, of course, there's the taxpayer money wasted—if we're going to employ that many people it may as well be doing something useful rather than attempting to stop all possible methods of bringing down an explosive tin can tens of thousands of feet in the air.