Having helped several kids build these birdhouses, I and I'm sure they don't care what kind of birds are housed by them. This is a project that when complete I always tell them "you just built a birdhouse". That always generates a smile and something they show proudly to their parents. This is not about making bird habitat, but about giving kids a sense of accomplishment. We are about woodworking education and not about bird conservation. If the two coincide then all the better, but is it not our goal.
Some of the kids that build these are excited to take them home and paint them - not the thing to do for a Bluebird house, but very much a thing to do to get them involved in a wood working project. That is our goal. We are not really trying to support the blue birds but to support woodworking education. Any inroad into that goal is important to us.
This discussion of whether we are making correct Blue Bird houses is getting way off track from our goals. That should be a separate discussion.
Sorry if I'm offending the Blue Bird contingent, but there habitat is not one of our goals as important as it is, we have to choose our goals.