Air Pressure Build up rate differences between Canada and the US

Hi , I am new to the trucking industry and have been creating my own checklists for Pre trip, Air brakes checks as the schools do not teach you what you should be taught when you try to land a job with a trucking company, rather they teach you what is needed or required of you to pass and or to appease the Ministries of Transportation so you can acquire your license.As well I noticed at my training center that most of the trainers are also not on the same page with each other as far as training methods go. They all have there own way and some students will obtain better and more information or instruction than others. My checklists are for Class A, or AZ Air Brake Inspection/Systems check, as well as Pretrip inspections both under the hood and around the tractor trailer, I have also created a checklist for Class B or DZ for Dump trucks and Buses.So to get to my question.
I have noticed a huge difference in the air build up rate time between Canada's regulations and the US regulations and , I am wondering why these would not be more in sync with each other seeing that we are all in North America.Ontario Canada allows a 2 minute air build up time and the States from what info I have found states a 45 second air build up time, also why are the procedures for carrying out theses system checks so different? There are nine steps in Ontario and I believe 6 in the States.They both serve to verify the Rig and trailers are safe for the road but again why are both Countries not on the same pg. Hoping someone can explain this to me.