Yes, there are institutional minimums.
We have a minimum for Ph.D. support. We have equalized tuition, so international students pay the same tuition as domestic students at the Ph.D. level, recognizing that McMaster is a research-intensive institution. However, funds need to come from somewhere. International master's students then, of course, will often pay disproportionately higher tuition, as a result.
Those are the types of trade-offs that we, as an institution, are making in our severely constrained fiscal environment in order to ensure we meet our research mandate while supporting our graduate students.