Usually, not at night -- but why close a local library in the evening.
Just require library cards and add video surveillance.
(you milage may vary)
But he wouldn't be surprised at all that homeless persons would be used as a pretext for spying.
Of all the surveillance methods, this one is nowhere near as intrusive as some others. The recordings will likely be overwritten/erased within weeks, if not sooner. Few operators of such cameras store the resulting video for extended periods of time.
On the other hand, Google probably knows your crush from 2005 and your diagnosis from 2009. This long term surveillance is what really messes with me.
Hopefully EU has bans against such things, but even that may not be enough.