No, unless Toronto City Council made major reforms to city bylaws under our noses. I'm have trouble finding the original document, but essentially only Toronto agencies (which includes the TTC) are permitted to collect fares within the City of Toronto. Remembering back to the Line 6 shuttle service a few years back, the operators had to creatively work around this and had customers pre-purchase a monthly pass instead of paying the fare upfront. YRT and MiWay are slightly exempted from the rule as they are permitted to ONLY drop off passengers while heading East/Southbound towards their destination within Toronto and pick up as they leave the city. TTC routes running within York and Mississauga are contracted so technically they aren't TTC routes when they leave Toronto. Wikipedia probably does a better job of explaining this,
https://en.wikipedia.org/wiki/York_Region_Transit#TTC_fares_in_York_Region
So Presto really has nothing to do with this, just lovely Canadian Bureaucracy.