Iranian SAM'S appear to be only using their optical appatures to target American planes, which means that they are quite easy to decoy. No doubt obviously due to the American planes also trying to bait Iranian radars out to shoot down their drones, than hit them right after. These Iranian Sam's, like the Iranian missiles, hide very very well, and unless the US plans to bomb every truck in Iran, it will take a while to get "air supremacy"
Also I suspect Iran has alot of its SAM'S healthy and are just letting America waste their standoff munitions until they get board and start using smart bombs enmass. Than they will pull out their sams and force America back at square 1. I mean, thats what i would do, and thats also what Vietnam did in the Vietnam war, just hide their advanced SAM's while SEAD is ongoing, than pull them out when they think they are safe.