I mean, after the Oklahoma City bombing in 1995 I remember seeing many video clips of the vehicle making its way to the building. Checking now, https://libertarianinstitute.org/articles/the-oklahoma-city-... says "A 1999 Freedom of Information Act lawsuit filed by investigative journalist David Hoffman revealed that the FBI had twenty-two video surveillance recordings of the Murrah building and surrounding area stored at the FBI’s Oklahoma City field office." Its Wikipedia entry links to https://web.archive.org/web/20170510090822/http://newsok.com... saying "Agents also examined more than 900 security videotapes".
If most cameras 'very frequently didn't work' then that means there were huge amounts of non-working cameras in the area. Which seems like an expensive waste of money.
I can well believe that some cameras didn't work - I already mentioned the bank robbery where the cameras had run out film months previously.
In any case, the original claim "No cameras 20-30 years ago" is simply not true.