Most companies are in regimes where basic human rights are denied - it is called Capitalism, descending from Mercantilism and Feudalism. That is only peripherally the point - assume that people are working in a "standard" business, and then talk about how to generate not interest, but attendance, at a learning opportunity on their off hour.
My experience suggests that a free lunch is a more powerful incentive than the equivalent money - more people will appear at a study or survey for a slice of pizza then they will for $10. Strange but true. Other than that, if you can get one bellwether from each physical work area, they can announce their attendance before lunch, and others will follow.