> Why would the public sector feel bound to support it

The underlying axiom is the Pareto principle - that you get 80% of the benefit from the first 20% of the work, and getting the last 20% of the benefit takes up 80% of the work. The private sector will stop funding after the first 80% of benefit (it's not profitable to chase the last 20%) but the public sector is usually mandated to support everybody so it is indeed required to put in that extra effort.