"rare socio-political star alignment that makes HSR and subways possible."is nonsense. EU countries have been building HSR for half a century already. Japan has HSR. China has HSR, nationwide. S Korea has HSR. At national/federal level. BRICS are next. The US is being left behind.
Your remark only holds true for US (and in particular California) politics and development laws, NIMBYism and the abuse of environmental process like CEQA [0], and how doing transit (in the US) involves coordinating multiple city govts and agencies - instead of it being a federal/state project. If Eisenhower's 1950s interstate highway system had had to be done like that and rely on permission from multiple local officials and govts and local revenue-raising, it'd be a patchwork mess too, if it had ever even gotten built at all. Eventually results in BART's 2003 Millbrae-SFO extension ($1.5b / only 8.7 miles of track). Address the root-cause, not the symptom.
After half a century of piecemeal transit in only some areas, this all causes the chicken-and-egg that US homeowners historically associate proximity to transit with negative property value.
As to the comparison to Uber, the non-viability of public transport in post-1950 US urban-planning cities/suburbs/exurbs is due to the low density, like why aren't there a grocery, cafes, services, banks, Amazon lockers, fractional car rental services etc. in/near any major transit node in the US? Amsterdam, Singapore, Barcelona prove you can have pleasant liveable world-class cities based on transit.
[0]: https://www.kqed.org/forum/2010101910935/balancing-need-for-...