As Ben says, it of course wouldn't be completely easy and would be risky for my local transit authority to significantly reduce transit pass prices, but it's also the case that it isn't just about revenue. They want to increase the use of passes to reduce the need for cash fare collection, which can slow buses down quite a bit.
Passes are aimed at commuters who are twice daily users, and as such should be priced at around 5 round trips. 5 round trips on the subway/bus cost $14.50* and a weekly city only pass currently costs $20.75. You can use a pass more often that, and also for higher priced regional rail trips within the city (and added benefit of off peak and airport trips), but the point is that a pass isn't worth buying for people who just use it to commute, and it should be if it's important to reduce cash fare collections.
*More for people who need to transfer, but point is for healthy chunk of commuters a pass just isn't worth it.
