Without getting too far into the financial organization of Dr's offices (I have some insight), the key issue is that both private practices and walk in clinics are monetized the same way.

The receptionists keep track of the patients that come through the door by scanning their Care Cards and noting the purpose of the visit. A Dr. is given certain number of units for each procedure, and a maximum number of appointments for each day.

The info is ultimately passed on to the provincial health authority that sends a cheque to office. It doesn't matter if the payee is a walk-in clinic or a private practice. (compare this to the US system where the office has to submit accounts to dozens of insurers all with different rules)

One difference from the US system is that there is no bureaucratic filter to determine if the charge is "necessary". More complex (ie expensive) courses of treatment which are experimental or require travel do need to be approved.

The clinics are typically set up by an entrepreneurial Dr. who tricks out an office with a few treatment rooms, and works 4-5 days a week. He or she then offers shifts to other Drs that don't have their own practices (they are younger, or have kids and only want to work part-time, etc). The Dr.-owner then keeps 30-40% of their receipts from the gov't insurer to pay their overhead.

This is the way that Drs here can leverage their income since there are a maximum number of patients one person can bill for each day.