From Union to Kitchener GO, the standard fare (E-Ticket) costs $19.40. However, if paying by PRESTO, the adult fare is:
1.
$16.32 if taking the GO train all the way to Kitchener GO (best way if you can catch a Kitchener train)
2.
$17.00 if taking the train to Bramalea and transferring to the 30 GO Bus (best way on Weekends and when trains terminate at Bramalea)
3. [just for comparision] a whopping
$22.93 if I take the 71 to Unionville, 56 to Bramalea and then the 30
All of these would cost the same ($19.40) using E-Ticket. When comparing (1) and (2), it makes no sense to me that PRESTO users are charged 68 cents more for an inferior experience (slower and less convenient).
edit: links updated with future date