I agree 100%, this is one of the most inequitable government policies I've ever seen in this country. The numbers are much worse than you make out. The program has spent more than 2.5bn (the projected figure) and we don't know yet how much. The subsidy was closer to 70% for a typical large battery install. The government's own gen cost report would have put grid storage 1.5x ahead on ROI.
Note that figures like $66m/GWh are projected costs based on projects starting today, not coming online today. They may not include 'balance of plant'. For better comparison you would have to look at the financials of recently commissioned storage.