Lol, can you elaborate on the $500 free TTC transfer please?
The TTC's official policy is that transfers are valid for a one-way continuous trip with no stopovers. Presto, however, is not properly set up for that. More or less, it's set up to offer a free 2-hour timed transfer except you can't tap on the same route twice in a row.
So, if I take the subway from Union to Dundas and do some shopping, then later I take the 6 Bay bus back to Union, I should pay an extra $3 for the return trip, but with Presto it's free. Another example is let's say I take the 514 Cherry from Yonge & King to Distillery Loop, I can take the 121 Front-Esplanade back to Yonge and Wellington, saving $3.
And there are cases where it even lets you tap on the same route twice. Since the 509 and 510 share much of their route, it doesn't look like it's allowed to charge you twice when tapping anywhere along Queen's Quay or on Spadina, i.e. I've tapped on a westbound 509 at harbourfront centre then eastbound 510 at Spadina and gotten it for free. I'm not sure if you could just go and tap 10 times in 2 hours all for free, but definitely a return trip along the same stretch is possible.
Additionally, I've taken the 506 westbound from University to Spadina then eastbound from Spadina back to University and only paid once. That one I can't quite figure out as even the exact corner/side of the street I tapped was correct both times. I guess it's such a small radius that it
has to assume it's inaccurate, and my Spadina tap might have been for a 510. I've also done St Patrick-Queen's Park-506 westbound to Spadina-510 southbound to Dundas-506 eastbound to University, a circle (well, rectangle) for free.
Also, temporary readers, i.e. for subway stations while under construction to receive faregates, have a location of "0", I've gone Union-St George-Union on one fare. Also if a streetcar/bus reader can't get a GPS fix, its location defaults to "0" or something like "Queen St E at Neville Park Blvd" or "Leslie Barns" and you can tap on the same route twice as those inaccurate reads are all treated like "0" from what I can tell.
Add all of that up, and I think Presto transfers have been live since what, end of 2015? Early 2016? I've definitely saved hundreds.
Moot point as of this August when it officially becomes a 2-hour transfer with no same-route exception. I've kind of enjoyed making a game of what kind of weird route combos I can take to get a ridiculously long run of free transfers, but it'll be nice just to not have to worry (well, except for running a stopwatch and running a bit faster when at 1h50min...)