I don't know the unit cost, nor do I want to, but something rated to survive a 16G event in an aircraft environment (the requirement since 1988) is always going to cost more to develop and build.
Rail seating wouldn't need to be built to that standard, but it still might be cheaper to buy off the rack than design something custom just for Amtrak.
China already has moved this way on their high speed rail. I don't know if European HSR or Russian rail offer something similar but it wouldn't surprise me. Privacy isn't seen as an essential human right outside the USA....
https://www.travelchinaguide.com/china- ... s-seat.htm
Tens of thousands of business travelers fly in this type of seat every day, and I'll guess that thousands of HSR travelers do as well. Those air travelers are willing to pay 3x-10x the coach fare (arriving at the same time...) to have that level of comfort/sleep, and have no problem not being able to shower until they get to their destination hotel or an at-terminal showering facility (which I used religiously after an overnight flight before running into a meeting).
Why the rail enthusiast community insists on hard partitions with private toilets for an overnight trip will always be boggling to me. I'll admit that on an multi-day land cruise, there may be demand for sleepers. But that's five or six trains out of the entire LD network. You simply don't need that for the overnight to Florida or Chicago from the East Coast.
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