The only individual electronic throttlebodies in use for street cars that I can think of are on high end engines like what you find on the S65 engine for for BMW E60 M5 or the 1LR-GUE engine for the Lexus LFA.
What you have here is a set of butterfly valves attached to a common shaft for each bank. Each bank needs its own throttle position sensor and a control method needs to be devised. For BMW, they control the two banks independently and coordinate between the two banks using a high speed data bus.
One of the main advantages is that the throttle valves are placed downstream of the plenum.
Therefore the software does not need to model a large delay/time constant to account for the filling of the manifold as charge air is moving from the airflow meter towards the cylinder.
This issue of time constants is one of the reasons why people run into fueling problems when they install a front mount intercooler on their WRX. The internal airflow model gets messed up.
If you are able to manufacture a part that works, it would still not be easy to control ITBs consistently. Of course you could do some basic lookup table but it would be an uphill climb to make it behave on the street. Who knows how many man hours went into writing Toyota's software for ITB control.