Ancient art of laying track is all but forgotten in Ameristan. Right? Jokes aside however...
1. Allied terror bombing did fairly low damage to railroads.
What was damaged was quickly repaired.
2. Even if roads are quicker to repair, crucial infrastructure, such as bridges, are not.>>1746269>That's the fate of a lot of highspeed rolling stock.
No, it is not. Heavily used rolling stock just needs regular overhauls ( 10-15 years ) because it wears down - especially interiors. But... TGV Pos have gotten between 37 to 42 years of service in them. Atlantique sets were built in late 80s and early 90s and are still run. ICE1 trains are still in service (30+ years) and are slated for withdrawal in late 2020s.
So. No. There is nothing special about HSR trains. They also are commonly used on secondary lines - like in France or Germany.
Acela is just a poorly made pork-pork and amtrak just wants to get rid of it ASAP.