Even if this system cost $20 million to set up, how much public transit does that buy you? 100 feet of subway track? 20 buses? 1 mile of streetcar track?
100 feet of subway track? I wish I could get those rates. NYC's latest Second Avenue Subway budget is $6.3 billion for 1.5 miles, or, about $800,000 a foot. You can get 25 feet of subway track.
California's not quite that bad, but, it's close to that bad. The Downtown Extension for Caltrain is $3 billion for a mile. SF's Central Subway is $923 million a mile. So sure, you can get about 114 feet of subway, but it'll be the short little LRVs and not like BART or anything nice-ish.
I'm told that, besides general competence issues and political-football games about who gets to builds the subway (contractors, ewwwwww) ... a lot of it comes from deep stations with onerous fire-safety guidelines that require massive mezzanines. These stations are mined out through narrow shafts instead of doing cut-and-cover, adding expense and inviting delays. See e.g. https://twitter.com/2AvSagas/status/1064907564230557696
But it's mostly the fact that the leadership doesn't care, doesn't have to care, and is actively incentivized not to care.
Last I checked, Vancouvers electric trolley buses (with the poles and the overhead lines) were ~1.5 mil Canadian, with the regular diesel buses costing only about a million Canadian.
buses are generally significantly less than a million per bus. BYD electric buses have a unit cost of about $750k which is "approximately double the cost" of a standard diesel bus
Transit is way more expensive than any cameras.