It's an interesting paradox between the conflicting demands of commerce, safety, and security.
Systems exist to integrate the data from a multiplicity of radar heads and provide a feed of the raw data. Having poured liberal amounts of wonga into developing this and providing and running the infrastructure to deliver it you then have to come up with a viable way of paying for it. It's not unlike the situation that exists with any map or chart producer.
While it's an attractive proposition to suggest low-cost feeds you get stuck with a number of issues. ATC provider A might justifiably complain at having to pay considerably more than ATC provider B for the same data.
From a safety point of view it's not difficult to foresee situation where pilots think they are getting one service but are getting another. (I have enough of a problem remembering the difference between RIS & RAS). If you add in the possibility of radar information being provided by units that are not radar qualified it gets more tricky.
And finally from a security perspective it's not difficult to see that certain persons would find easier access to radar feeds of some practical use for nefarious activities.