And good grief - if Quebec transit agencies can supplementally handle Presto cards for transfers - then surely GRT, partially funded by Ontario, should have been able to do it.
To be fair, only STO has done this. And they have a completely separate fare system from the rest of Quebec which uses Opus. And Presto is only usable on STO with a monthly pass stored onboard and a transfer after tapping on OC Transpo. Pay-per-trip is not possible to be initiated on STO.
I do agree that it's bollocks that GRT was not compelled to use Presto by the province, while Ottawa was put through hell converting over. Especially crazy when Waterloo is so close to the GTA.