Even if you started building it you pick winners and losers with which town gets a rail station. A dozen commuter lines extending out in a 35 mile radius would be seriously impressive as a new network anywhere in the world really, yet that only means a dozen towns 35 miles out see a connection, the rest don’t. This also demands high speed rail to compete with cars; a typical american commuter rail going 70mph top speed with a dozen stops of some interval including acceleration and decelleration plus a potential transfer to a local line or bus to get to work from that commute rail station is some serious time to make up, compared to the case in all but a handful of american cities where even during rush hour a more or less fully built out freeway dual ring and feeder network is flowing at 70mph with no stops in between.