Tracks do last forever with normal maintenance and partial replacements. Rails do wear out, and are constantly being realigned and replaced, as well as ties, ballast, signaling etc.<p>But your point about rolling stock is correct. The PCC street car was designed in the 30&#x27;s to address that, being a mass-produced, modular system.<p>Also, the European streetcar systems went through the same economic hardships (and some much larger ones - the wars), even using the same PCC cars, but still thrive to this day.<p>So it is more about a policy driven by lobbying and intervention from auto manufacturers than purely business model and economics. Robert Moses had a really big hand in this as well...