No - subway trains can travel 50 mph or more - a bus can’t do that on city centre roads.
If you have really comprehensive coverage in a densely built area you'd be stopping too often for those top speeds to matter.
This is the problem with the Acela. It can technically go up to 150mph, but it has to stop so often that it averages 60mph for the journey.
For longer distances with limited stops, the speed and shigh capacity of a train are good. But to really fill out coverage in a dense area, short wait times and short distances between stops and destinations should be your chief considerations. Buses and streetcars just do that better. Though really, once you get past a certain level of density you need all of the above.
https://ny.curbed.com/2018/12/19/18146933/mta-new-york-subwa...
New York's system is designed around walking to stations. All the way to the end of the lines, stations tend to be about a half mile apart. There are express lines but even those become locals on at least one end, with half-mile stop spacing.
DC's is an auto-oriented system, where you're expected to drive to the stop and then take the train in from the suburbs. As a result, while there is dense stop spacing in the center, distances between stations in the suburbs get progressively longer and longer. It's over these long stretches in the suburbs that DC is able to attain much higher speeds.