Qassam and related rockets are little more than steel tubes with an explosive warhead. They are unguided so far as I can tell, and to the extent that they're targeted at all, this is likely based on the launch direction, angle, and fuel load. These are weapons of terror and area denial, not precision strike weapons. They land roughly at random. Missile accuracy is described by CEP, circular error probably. I can find no information on the CEP of Qassam rockets.
Wikipedia has images of the rockets in this article:
<https://en.wikipedia.org/wiki/Qassam_rocket>
The (current) top image shows eight launchers, literally just welded box-steel frames, roughly 2 meters tall. I presume these can be stored under cover and rapidly assembled in a clear space for a launch. There are no electronics, radars, control vehicles, etc., which is to say, there's very little to detect.
<https://en.wikipedia.org/wiki/Qassam_rocket#/media/File:Flic...>
The contrast with IDF's precision munitions which strike a single building from multiple angles to both perform a "roof knock", then implode the structure, couldn't be more stark.
<https://en.wikipedia.org/wiki/Roof_knocking>
Example of "roof knocking" (shown after the implosion, the roof knocking of course occurred first), followed by three strikes to the left, centre, and right of the Palestine Tower in Gaza, on 7 October 2023:
If you have actual intel of your opponent in a building, you take that out and collateral damage of human and infra comes with it but when you "warn" the people that a strike is incoming, what's the point?
I think there is also an element of PR in addition to genuine concern for collateral victims as this is an urban environment and Israel knows they will inevitably be accused of wrongdoing.
Note that civilian buildings are purposely used to store military assets.
actually depending on collateral damage strike could be cancelled. till bomb/rocket is released it's tentative strike. there is footage here and there of cancelled strikes.
additionally IDF made some long multi-disciplinary research with ethicians, lawyers, mathematicians, etc about how to balance target (priority, level of immediate danger aka ticking bomb, long term implication of target staying alive, etc. it's not really published) vs acceptable collateral damage
we almost live in the world of "minority report": you get ads for the stores you were near recently.
the effort it took to coordinate "5,000" launches or however many it was probably wasn't missed.