I don't know anything about TACC except I read here as I do not have my Tesla yet. But let me tell you my software developer's opinion and experience with my BMW's ACC that I drove for about 300k kms in the last six years. This system works and sees even bycicles. The only condition is that it has to move in the same direction as the car. If it's stationary (approaches the car with the speed the car is going) or is oncoming traffic (approaches faster than the current speed of the car) then it will not react, even if I will collide with it. It was presumably designed like this to be useable on narrow two lane roads with heavy oncoming traffic. And it works well, even on winding roads (with some limitations, basically the same ones that are described in the Tesla manual). So don't you really set your expectations too high for TACC. My two cents.