I guess Boston is one of those rich cities. There are swarms of business people commuting through the city each morning and night. I was not aware of anyone calling them bums. All of the people that ride the bike paths at night were unaware that it was illegal. The dedicated 10mi long bikeways like the Minuteman Commuter Bikeway are especially useful. 5000 lumen bike lamps help too.
Also, why would you want to bike on the shoulder of an interstate? The whole definition of a limited access highway is that only highspeed cars, going the same direction are on it, for safety.
Laws vary significantly by state. I'm pretty sure it's legal to ride on bike paths at night. In Washington you're required to have a forward-facing light and a rear reflector. It's also legal to ride on the sidewalk, unless you're in Everett.
As for biking on the shoulder of an interstate, there are areas where the only paved road going between two points is an interstate highway.
And of course there are very common borderline cases where I want to get from point A to point B, and the path on the interstate is 50 miles, while the path avoiding the interstate is 150 miles. So a trip that I ordinarily need to allot one day for becomes a 2-3 day trip unless I'm willing to pedal at top speed or for more than 8 hours. I don't want to bicycle on the interstate, but most infrastructure assumes your bike is a purely recreational vehicle.