I'm definitely not an expert, but from what I've read, there's a lot of irony in the angular look of the F-117a becoming the icon of "futuristic". That plane, first of all was designed in the mid to late 1970s. Second, notice that newer [stealthy] planes don't look the same? What people say is that the facets were purely a necessity to simplify the calculations needed to make it stealthy. People did incredible things when computing power was expensive to solve problems analytically, which became obsolete once you could just apply brute force.

Also, I don't know about the business of making movie props, but it seems plausible to me that when making cars for SF movies, decades ago when budgets were lower, probably involved large sheets of plywood, cardboard, foamcore or whatever, hence big facets would be the most expedient design.

It's weird how arbitrary so many signaling mechanisms are.

Unlikely. The F-117 looks like a "low polygon" airplane because it literally is a "low polygon" airplane. The 3d electromagnetic field solvers running on the fastest computers available at the time of the development of the F-117 were only capable of simulating an object with a small number of facets so engineers designed an airplane that could fly with a minimum number of polygon facets.

It is probably invisible to Tesla Autopilot.

I do too. I think the design is beautiful and unique. I also like that the doors are hard to dent and that I can get from 0 to 60 in less than 3 seconds. All great qualities, as far as I'm concerned.

I've already ordered one and look forward to driving it around in two or three years.

That would be fascinating if it could. IIRC there is an urban legend that the stainless steel St. Louis Gateway Arch is almost invisible to radar. That being said DeLorean DMC-12s are not invisible to radar speed detectors so I would doubt the Cybertruck is.

Possibly more/less visible. Speed radars reflect off surfaces facing it. In practice that means the front, the reg plate, sometimes the side mirror for most cars. For the cyber truck it's going to be extremes depending on the radar location - completely front facing one may be hard to bounce, but the ones over the street may hit the flat front perfectly.

It still won't work around speed cameras like the ones in UK (it's both a radar and photo camera) or variable speed cameras which use reg recognition.

I'm pretty sure LIDAR speed detectors are a lot more common than radar these days.