Not all countries with large rail networks have great suburban public transport either; the UK comes to mind.
Even in a mostly suburban metropolitan area, most people are still quite a ways from the main airport, which is usually on the extreme of one side of a metropolitan area. You can have multiple train stations per city because of their much lower footprint and nuisance level, and generally speaking most of the time savings in rail vs air is access time to the station/airport. (Truly high speed services can just skip the suburban stations if there truly is demand for this, but generally speaking the time for an additional station is measured in single-digit minutes.)
While the UK does not have great suburban public transport it is far better than what is available in most of the US.
Ironically car dependent cities like LA were built out as streetcar suburbs so they’re not really all that different to London’s ‘metroland’ suburbs built out around tube lines. The big difference is the job centres are far more distributed. When offices as well as homes are widely distributed public transport becomes very tricky.
Even in a mostly suburban metropolitan area, most people are still quite a ways from the main airport, which is usually on the extreme of one side of a metropolitan area. You can have multiple train stations per city because of their much lower footprint and nuisance level, and generally speaking most of the time savings in rail vs air is access time to the station/airport. (Truly high speed services can just skip the suburban stations if there truly is demand for this, but generally speaking the time for an additional station is measured in single-digit minutes.)