This is because, for the most part, scientists are focused on their research subject and their area of expertise, cost reduction, not so much. You can't really expect everyone everywhere (especially outside of engineering) to know the intricacies of arduinos, NI DAQs, etc. as well as how to best implement them. That's for the engineers, really, and having and extra engineer on the research team most likely costs more than the savings they could help with...plus I'm not sure how many, say electrical engineers, would be interested in that kind of work anyways.