Still don't get why anyone who uses the TTC as their everyday transportation would use Presto. You could easily end up paying more than the cost of a Metropass. Why don't they make Presto have a limit of amount taken out every month on TTC trips that maxes out at the Metropass fare?
This has been addressed hundreds of times by official sources, let alone discussion here and elsewhere.
Presto has not been fully rolled out on the TTC. If you take more than however many rides in a given month, it becomes more economical to purchase a metropass. Presto is not currently intended to replace a Metropass. "You could easily end up paying more than the cost of a Metropass" - yes, the exact same is true of tokens/tickets or the cash fare, this isn't a new development.
Next year physical metropasses will be discontinued, however before then you will be able to purchase a "digital metropass" that is loaded onto your Presto card, as with other transit agencies like YRT and OCTranspo. However, as I said,
presto has not been fully rolled out on the TTC, its deployment is
in progress, i.e. not complete, i.e. some things are not available yet. While I feel that the rollout has taken much longer than necessary, keep in mind that the TTC is a very large system, if you think they're having problems with Presto now imagine if they tried to flip a switch one night and have everything go from 0% presto to 100% presto instantly.
As for "Why don't they make Presto have a limit of amount taken out every month on TTC trips that maxes out at the Metropass fare?" there are two ways to do monthly passes--the way you described, which is what GO uses, and loading a digital "metropass" onto the card/paying up front for it, which is what most transit agencies e.g. YRT, OCTranspo, and soon the TTC will be doing. Why? Various reasons have been postulated--likely, the TTC views this as a useful cash float since they get money up front for rides that are taken later on, and as a way to make money because some people will end up paying for a pass but not taking that many trips, or some might end up not buying a pass but taking so many trips that they pay more than a pass. Switching to capping for monthly ridership, while great from a rider perspective, would undeniably be a small, but not insignificant, loss of revenue for the TTC, which given their constant state of financial starvation simply is not feasible in the foreseeable future.