This is basically the question that came to us today from our procurement office. The resources in question were several specialized A&I Databases. The query was for further justification on why we couldn't use other free search engines like Google. I might have been able to deal with a reference to Google Scholar better, as it's a little more focused than just searching the web. As it was, we were surprised, but took it for what it is - a basic lack of knowledge from the general public on how libraries work and how information is really provided.
I began the justification by pointing out that the products in questions were not search engines but Abstract and Index databases, with definition, added what made them much more than Google and ended by saying they were vital to the support of the curriculum. I hope it's enough.
I want to shake my head and say this person should know, but really why would they? The majority of people can find the information they need on the internet. The average user doesn't distinguish between a database and a search engine. Hopefully, this person will now be a little more educated.
This is actually the second justification for electronic resources I've had to help with (our Acquisitions department handles this end of renewals/purchases) and I suspect it won't be the last.