There wasn’t any air surveillance. That was the first and probably biggest failure. May their lives be filled with lawyers.
The lack of air surveillance and people on every roof was caused by the Biden Administration refusing to provide sufficient resources to the Trump SecServ detail. This is from multiple sources.
The rooftop was reportedly outside the SecServ perimeter.
The lack of local cops on the roof was likely a lack of SecServ money thing.
The Feds compensate for local police overtime supporting the protection of the President or party nominee for President, if I recall correctly.
...Which we the taxpayers will get to pay for. :-(