With indoor environments, everything is nice and comfortable. It does not rain inside, temperatures and humidity are controlled, the sun does not shine indoors, ambient light conditions do not change, the air is clean, power is consistent, the wind does not blow, and vandalism is rare. Basically, digital displays that are deployed indoors are in a controlled environment in virtually every respect.
However, in transit-type settings, everything changes — and it changes dramatically. Most transit venues are outside (like bus shelters) or semi-outside (like train platforms, subway entrances). Even when they are underground, these venues are not as clean and controlled as true indoor environments like shopping malls … not even close...