SW03ES: Sorry it took so long to reply to your post, but it has been quite a while since they kept my RX300 overnight (actually 3 days while they remove the resonant vibration in the headliner, fix the dashboard squeak (twice now) and remove the 'chirp' noise from the rear seats). <_<
Anyway, Lexus gave me a loaner 2004 ES300 (I have it in my garage at the moment). Now I have been testing this car for torque steer for the last 2 days. I don't know why yours does not have any torque steer, but on this one, at full power and full acceleration (from a stop), I frequently have to wrestle with the steering wheel to keep it going in a straight line. Lexus may have done an excellent job with minimizing any torque steer inherent in the drive train, but they cannot factor in pavement and road variations. Under full power if one wheel gets less traction (say a bit of gravel on one side of the road, a touch of oil on the other side, or a rut in the road) then one side of the front wheel drive will pull more than the other and you have...torque steer. The only way to remove this is to separate the drive wheels from the steering wheels (i.e. rear wheel drive).
Under low and moderate acceleration I can detect no torque steer, but under full acceleration it is definitely there.
Incidently, I am very impressed with the power and acceleration of this ES300.