Public transport is already more efficient from the get go [1], so less work has to be done to meet emmission targets. It is also probably easier to electrify a countries rail/bus network as opposed to a full population's personal vehicles. Steel on steel also releases less dangerous pollutants like car tyres. [2]

Public transport also comes with many other benefits over cars (quieter cities, less deaths from collisions, fitter population).

For super low population density locations cars will probably remain the only possible solution, but for most of the population we really need to implement a movement away from car dependence.

[1] https://assets.publishing.service.gov.uk/government/uploads/... Page 3

[2] https://www.emissionsanalytics.com/news/pollution-tyre-wear-...