Fair enough. I have never lived in Boston myself, so I can't speak to its specific issues.
Some school systems in the US are subject to judicial desegregation orders, so that the racially-divided neighborhoods do not result in segregated schools. These may require transit routes that are not necessarily coincident with the daily work commute. Some systems also have magnet or specialty schools. Some have even greater ability to choose (or win via lottery) a school other than the nearest to one's home. As a result, the commute for one child could be longer than that for their parents, and using the regular public transit could result in hours on trains and buses. In such cases, a school bus would essentially be an express, with no stops between school and the residential neighborhood.
And, of course, once you run one school bus, that means you now have a school bus infrastructure, which makes it easier to run more buses.
The public transit system is usually designed around moving people between workplaces, mainly in the city core, and homes, which are more evenly distributed. Schools are also more evenly distributed, as villages, towns, smaller cities, and unincorporated townships may have had one or more of their own before being annexed into the metropolitan city. As a result, the nearest transit station to both home and school may be the same station. Or they could be on lines that run nearly parallel before meeting in the downtown hub.
One possible solution to this would be to build a large, unified school near the city's central transit hub. And that would likely be selected by an algorithm as most efficient. But politically, people prefer their schools to be near their homes. And separated by grade levels. With athletic fields and playgrounds. And lots of separate and distinct administrative regions. Again, the technically sensible solution is untenable, because people just want what they like (and what makes them money).
Some school systems in the US are subject to judicial desegregation orders, so that the racially-divided neighborhoods do not result in segregated schools. These may require transit routes that are not necessarily coincident with the daily work commute. Some systems also have magnet or specialty schools. Some have even greater ability to choose (or win via lottery) a school other than the nearest to one's home. As a result, the commute for one child could be longer than that for their parents, and using the regular public transit could result in hours on trains and buses. In such cases, a school bus would essentially be an express, with no stops between school and the residential neighborhood.
And, of course, once you run one school bus, that means you now have a school bus infrastructure, which makes it easier to run more buses.
The public transit system is usually designed around moving people between workplaces, mainly in the city core, and homes, which are more evenly distributed. Schools are also more evenly distributed, as villages, towns, smaller cities, and unincorporated townships may have had one or more of their own before being annexed into the metropolitan city. As a result, the nearest transit station to both home and school may be the same station. Or they could be on lines that run nearly parallel before meeting in the downtown hub.
One possible solution to this would be to build a large, unified school near the city's central transit hub. And that would likely be selected by an algorithm as most efficient. But politically, people prefer their schools to be near their homes. And separated by grade levels. With athletic fields and playgrounds. And lots of separate and distinct administrative regions. Again, the technically sensible solution is untenable, because people just want what they like (and what makes them money).