Around 70% of the time I'm in an underground LRT station, I see janitorial staff. The big problem is that there's a lot of ground for them to cover, and a lot of disorder that leads to this cleanliness issue. I'd love to see the city put more resources into this, but I think the first step is actually to increase peace officer resources so that they can do more proactive patrols, and cut down the disorder.
Regarding cameras, I got a peek inside the control centre recently, and it's not possible for them to monitor to that extent right now. They have three huge displays, and each display shows one or two dozen feeds. But they have ~7,000 cameras system-wide, between the stations, buses (newer buses have 3 cameras), etc.