Looking at the scenarios you laid out above, have you implemented any strategies to address them? I don’t know your market but here are a few ideas I came up with as I read through your post.
1)Are you making money on the pre-wires (when you do get them)? Or is the only reason for doing the pre-wire to get the equipment sale? If the latter, have you considered partnering up with the electrician and/or builder and specifying what/how the wire should be run. Granted, this would mean you would have to stop looking at the electrician as the enemy and instead as an allay. Then establish upgrade options for the builder. See point # 4.
2)An alternative attack would be to establish a great relationship with one of the clients whose homes you have to correct after the electricians poor wiring job. Get the homeowner to write a letter to the builder telling him how disappointed and upset he was to find that the low voltage wiring provided to him for his brand new house was inadequate and didn’t even provide for the basics. How many letters do you think it would take like that before the builder would be afraid to let that electrician do another pre-wire?