So that might work for some cities. In Chicago, where I live, the open space surrounding most train stations is literally just the sidewalk. A few train stations also serve as hubs for the buses, and those have enough space for that amount of bike storage, but they're a definite minority.
I'm not familiar with Chicago, but do you mean a street like this [1], under Carl/Lake station? It has two lanes given over to parking cars, plus a parking garage in one of the buildings.
At Nørreport [2], there is no car parking, except a taxi rank for three taxis.
A little further away from the city centre, at Forum metro station [3], there is a little car parking, but still plenty of space for bicycles.
There are counterexamples — parts of London or Rome, for example, although these areas are often so compact that there's little reason to leave 500+ bicycle in one place.
