Tim Hortons review: Why the doors are chained closed

Why would the doors be chained closed but not locked at Tim hortons location 6966 Financial Dr, Mississauga, ON L5N 8J4. Does it not matter that snow plow for truck drivers deserve warm food or hot coffee or simply use the use the washroom. Unfair as they can't fit in drive thru. Also why was there no note saying that to doors are locked. When knowing on the window the staff didn't even look at my direction as to tell me to go thru drive thru.