I’m feeling sea-sick looking at that picture. :-) Interesting way to look at the triggerer issue. Great idea. I agree the taxi would be in a more difficult position to trigger the IED. However, there’s always the possibility of “luck” and that they had four chances to hit a vehicle.
You mention the alleged “trigger house” (to the North) would be blocked by buildings on the north. What about if they were on the roof? Seems like a lot of these houses have flat roofs that are easily accessible.
Logically, the general location of house 1 makes the most sense. What can also be noticed in looking at these pictures, is house 1 would likely have known about the placement of the IED in the first place. The IED was placed in the road and paved over to match the rest of the road. I’m assuming this would have taken some time and made a bit of noiese to tear up the original pavement and redo the pavement. Even at night, it would be hard to believe it wasn’t noticed.
Remember GE ( GoogleEarth ) exaggerated the slope, it’s possible they could see, but the only real clear shot we can see is the 25m before.