Please avoid paternalism when taking.
Air defence has different modes, how do you think is that Ukraine make ambushes to Russian planes with a Patriot of other means?
If the radars would be active the planes would see the anti aircraft system in its own radar.
The procedure is to use the radar in passive mode to avoid emitting signal and only activate it when you are going to shot, in order to direct the missile to the target.
This is the fire control you talk about.
When you know the target plane is close, and this is mainly visual, you activate radar and shot.
The ISR is mainly use to analysw the common routes of planes and place there the air defence for the trap
that's the problem with ground combat in complex environments. It is very messy. You can easily have ambushes and surprises against air assets because of forward spotters hidden in mountains or in trees, a few guys with MANPADs waiting for helicopters, etc.
naval (and desert) combat is cleaner. I already went over why Taiwan won't have the opportunity to pull what Ukraine does - they'll be forced to turn on their radars, since there won't be forward air observers in the strait.
But can Taiwan proactively attack? No. Their ground based long range missiles attempting to strike targets in mainland China must overfly not just the strait but also a large chunk of Chinese territory that will have forward observers and combat air patrols. The only way to avoid it is to strike coastal targets - but there aren't many stationary coastal targets of military importance. Their only option would be terror bombing Xiamen or Fuzhou which would be military ineffective and only harden resolve against them.
And if Taiwan cannot strike a significant number of PLA air bases with cruise or ballistic missiles, their relative sortie rate will plummet as PLAAF can continue sorting planes while their operations are severely disrupted by missiles and drones falling on them. The actual number of aircraft in the air is related to sortie rates, not to total plane count. A plane on the ground doesn't do any good.
