No idea what an AirTrain is. Do you mean UP Express? Why stop at Weston and pay $5.30 and not just take it all the way downtown for a meagre $12.35? During heavy traffic your travel time would be roughly equivalent to a cab.
AirTrain = Linktrain [1]. Take it to the alt-hotel (for free) right at the airport and grab an Uber Pool to save 50-60% of the cab fare and get dropped off right at your door step with all your luggage.
I drove a guy who was trying to make an app which would do this, but I can't remember what it was called. It started as a Vancouver-Whistler ride share e-mail list.
There is on Lyft: https://help.lyft.com/hc/en-us/articles/213586028-How-to-use...
How do they impound the vehicle if the driver is in it? Do they arrest the driver first?
In some cities Uber drivers are able to choose drop-off areas, but I don't believe Montreal is one of them.
Interesting side note the driver actually was an airport employee - he would drive for Uber twice a day, once to work (he would hang out by the area of the city with lots of Hotels to try and catch and airport trip) and once on the way home. I thought that was kind of awesome.