In winter the only spaces that are warm and publically accessable are the transit stops and bus shelters, so of course people with no where else to go would use them to stay warm and not freeze to death.
Can you guess what the city did to "fix" this?
They renovated the train stations to remove the warm sheltered waiting areas in favour of semi-enclosed glass waiting areas that technically have heaters but they're open to the elements so they don't do shit. They've also removed bus shelters and even benches at bus stops, and they make sure to have the pigs do sweeps of the transit system to remove "undesirables". I haven't paid for the subway since my university pass expired but since I look like a they just glance at my (empty) card and move on
It can get down to -40 here so they have to pretend to care about the cold, but I can tell you from personal experience the heaters they do have don't do jack even when it's warmer