The freedom free software gives users is usually thought of in terms of usability, auditability, modifiability, and distributability of code (or mistakenly thought of in terms of cost). Some or all of these freedoms are disrespected with proprietary software. Typically, those who engage in the drafting and enforcement of proprietary licensing do so to hoard. Though unethical, hoarding at the expense of users’ freedom is not nearly as unethical as this.
Link thanks to Dave B.