A response from a CSR from Shaw after emailing them my concerns after my initial phone call:
"Thank you for your e-mail, your input is very important to us, as we strive to deliver the highest quality TV viewing possible. We understand your frustration with this interruption and we do endeavour to avoid these situations occurring at all times. We sincerely apologize for the inconvenience caused to you. Shaw Direct is required to implement Simultaneous Substitution whereby the signal of a US station is entirely replaced by the signal of a Canadian station only when both stations air the same program at the same time. This is a CRTC requirement and must be followed by all major cable companies and Satellite TV distributors. It is designed to protect the rights of Canadian broadcasters. These regulations permit Canadian broadcasters who purchase American programming, to use signal substitution as a means to earn advertising dollars.
Basically, for simultaneously broadcast programming on US over-the-air channels and Global stations, we will now be doing simultaneous substitutions over broader areas, like so:
>§ Global Maritimes to cover the Atlantic region;
>§ Global Montreal to cover Quebec;
>§ Global Toronto to cover Ontario (except for the 75 km area surrounding Thunder Bay)
>§ Global Toronto HD to cover Ontario
>§ Global Winnipeg to cover Manitoba
>§ Global Saskatoon to cover Saskatchewan
>§ Global Calgary to cover Southern Alberta (Red Deer and south)
>§ Global Edmonton to cover Northern Alberta
>§ Global Vancouver to cover BC
Right now, we only do the substitutions over a 75 km range surrounding a broadcasting city. In addition, for Ontario customers, we will also be simultaneously substituting Global Toronto over Global Montreal for simultaneous broadcast programming. While more customers will experience simultaneously substituting, it should not affect service quality, as it is ONLY for simultaneous broadcast programming/episodes. If this trial is successful, Shaw Direct viewers will have the benefit of receiving more relevant local news, weather, and sports updates for simultaneously broadcast programming."
So, it has been confirmed via email of what I (and others here and elsewhere suspected). The last step is to double-check tonight if CTV or any other Canadian network is simsubbed in my area (I couldn't last night as I was busy), and then we definitely know what Shaw's motives are... not to provide us with a better local experience, but to make more $$$.