Here's why the monthly cap option is superior to a monthly pass (and by monthly cap, I mean you pay per ride until you reach some point where you become free until the end of the month):
1) Transit is made more affordable if you can reload your card once a week instead of spending $110 in one sitting. Currently, those who cannot afford a monthly pass are forced to use tickets that have a higher per-ride price. A monthly cap gives you all of the discounts of a monthly pass but without forcing a large pre-payment.
2) Monthly passes cannot be pro-rated, while a monthly cap can. There's always a chance that you will not ride enough to justify the pass, but you will not get your money back. With a monthly cap you only pay for what you use - and if you use it a lot you'll reach the free point.
3) Monthly passes require you to guesstimate how many times you will ride in a month. If you don't buy it and you go over then you'll pay more. If you buy it and then don't ride then you'll pay more.
On flat fare systems with a timed transfer, all the computer needs to know is when the card was last tapped. If tap two occurs within 2 hours of the first tap, the trip is a transfer. Else, the trip is a full fare. One only needs to tap off if we're doing fare by distance, but that's a separate discussion.
all you said makes a lot of sense and should be implemented.
However, I doubt it will ever happen, simply because the TTC following the same logic, has and will squeeze each cent out of its customer's pockets. A monthly cap is adopted in the London Underground, which works great. I loved the flexibility of not having to pay for a monthly pass when it turns out you didn't need to, or regretting not having bought a pass when the total trips made it cheaper. But will TTC like that idea? Absolutely not. I doubt the majority of passengers make more than 48 trips each month, but hey, wouldn't it be nice to make them pay for that many trips?
Among the public transit system I have taken, TTC offers the minimium customer flexibity.
For example, some cities offer a 24 hour day pass, which means if you buy one at 1pm today, you get to use it until 1 pm tomorrow. But TTC doesn't. If you realize you need to make multiple trips at 4pm, you can only use the pass until 12am (or whenever 5am for the bus I think).
Some cities (Vancouver) give a 2 hour transfer window, allowing you to board any bus in any direction during the 2 hours. But TTC doesn't. No return trip. No walking to the next stop. There was one time my friend was taking the 34 eglington and mistakenly got off at "Yonge/Eglington" station instead of "Eglington station" without knowing the latter's existence. Although with a transfer and the two stations are like 200 meters apart, he was denied access and asked to pay again.
Other cities offer discount price for non-rush hour (London/Paris etc), or a monthly/daily cap etc. TTC doesn't either. It is either $2.5 per trip, or $121 per month. Make your decision on the 1st of each month!
Yes, the TTC is the most stingy to its customers with its 1985 technology, 2 line subway system, completely unpredictable bus schedule and one of the world's most expensive fare system. I literally have not experienced anything worse.