IIRC..... it's voluntary for the property owner. A business that leases property within a CFD would be subject to whatever the landlord wants.
A new tenant can always lease elsewhere if the cost at Westgate is too high.
Since other commercial space is not directly affected by the CFD, part of any levies could be borne by the tenant (if the CFD makes Westgate space more expensive than other commercial space); part could be borne by the landlord (if it has to reduce its net rent keep the gross rent competitive with other commercial space); and part by the consumer (if any part of the levies can be passed on in the form of higher overall prices for goods and services).
If I lived in Glendale and were looking for big-ticket items like furniture, electronics and automobiles, I wouldn't care to shop at Westgate if it had an additional levy, no matter how small, unless there were some other competitive advantage to shopping there. If I wanted a snack before a game, the levy wouldn't make any difference to me, but everyone is different.
How much is ultimately paid by the tenants, how much is absorbed by the landlord in the form of reduced rents, and how much is passed on to the consumer would sure be hard to tell after-the-fact, let alone in advance. However, it sounds like the cost of any CFD would be shared by almost everyone connected with Westgate. This must give the major stakeholders cause for some pretty careful consideration as to just how valuable the hockey team is to the surrounding businesses.
If it were truly voluntary, there would be no need for a CFD at all. The stakeholders could just privately fund the hockey team, and their returns would even be higher. It has to be compulsory to conscript freeloaders who would reap the benefits without contributions. That's the whole idea of a tax.