If a customer is not planning to distribute the software outside their organization, then they can modify open source-licensed software ad infinitum without having to contribute a single line back.
I've seen many companies who still believe that any IP developed on open source must be placed back into the public domain. A little education and a few "marquee account" case studies will help to combat these points. In addition to free passes for an annual event, maybe the OSBC could sponsor webinars on this topic to proactively educate a broader audience?
Over time these barriers will come down -- any companies leading the charge will certainly enjoy massive growth.