You must be talking about the ZSU-23-4 Shilka actually (AAA), since the Strela is an IR-homing SAM launcher, and does not have a radar.
And yes, I think the AI of Shilkas is definitely smarter. The Shilka can only fire at a range where the enemy aircraft is visible, so the radar is just there to help ith accuracy, not to detect the targets. And because the Shilka commander doesn't want you to spot him from 10 miles away, he just switches the radar when he wants to soot at you !
Anyway, IMO short range SAMs and AAA (Shilkas, Vlcans, Avengers, Strelas, etc...) is to be taken out with short-range weapon systems (Vikhr, KH-25ML, S-25L...). You need to look more carefully to the vehicles on the ground, but with a magnification of x23, I assure you it's not that difficult to distinguish a Strela from a UAZ ;)