I'm in a considerably colder climate than you and my CX-9 sounds like a different car altogether. While I agree that the heat isn't as good or as "fast" as my other cars, I know that there are reasons behind this and they make sense to me (larger cabin to heat up, 4cyl vs. V6). It's definitely a shortfall in the CX-9.
With that said, my driving habits seem to lend themselves well to the way the CX-9 operates. By this, I mean that I'm not one to turn my car on and let it sit for 20-45 mins. That's just obscene to me, it's a huge waste of gas, bad for the environment, and bad for the engine. I'm the kind of driver who turns on his car, straps on the belt, sets navigation (if necessary) or changes a playlist and I'm off. The engine warms up much faster this way, and as such, the cabin warms up faster as well. Some things to note:
1) Heat output doesn't drop at stop lights or in Park
2) Heated seats work well, even through a padded seat bottom cover
3) Never had any issues with frozen washer nozzles because I use the appropriate washer fluid
4) Rear defroster works perfectly fine
5) No washer fluid warning "light", but there is definitely a low washer fluid warning that overtakes the info screen
6) Despite the lack of vents, I haven't had any issues defogging the 2nd row and 3rd row windows
(shrug)
You guys have got me wondering what else they sneaked into the 2018 model or firmware updates. Maybe the low washer fluid warning was added in the firmware update I have in my CX-9? Maybe they added vents to the 2nd and 3rd row that I didn't notice?
EDIT: I don't think that anyone should have to do this, but if it's absolutely necessary, maybe you guys can look into getting a block heater and/or an oil pan heater installed? I wonder if those will help with your vehicles?
I think the Canadian models have some slightly different features, such as the low washer fluid warning (and perhaps this was added to US models after 2017, but I'm not positive). In my previous cars I used to start it up, get in, and go but because my CX-9 took so long to warm up when driving I started to let it run for a few minutes before heading out in the winter (when it's below freezing). "Warm-up" time progressively got longer and longer until just now that I learned that the car/cabin doesn't actually warm up. Now that I know it's a waste of time/resources/energy I guess I'll just "suffer" driving for 10-15 minutes with no heat.
I was looking at block heaters today and unfortunately I don't think this will address the issue of the cabin not heating up: since the thermostat does not open until the car's RPMs are above a certain point (~1,200 RPM) having a warmed up engine at idle will not speed up heating of the cabin. It seems the only way to heat the cabin is to drive the car with little to no heat and wait for everything to warm up. Worst of all, this was a conscious decision by Mazda to have the thermostat/heat function this way.
Some of the items I listed are not major or every time driving occurrences, just things I've noticed having had the car for a year and a half and comparing it to other cars I've had.
Heated seats do eventually get too hot on 3 and I have to turn them down to 1 or 2, but it just takes a lot longer than my VW.
For washer fluid I always use Prestone AS-250 De-Icer fluid (the yellow stuff) which has worked great in previous vehicles and never froze up...until I put it in the CX-9 (or mayber it was snow/ice buildup that froze on top of the spray nozzles, but still, the heated nozzle feature would prevent this problem).
It's only been a handful of times where the rear windows remained fogged up even though windshield had fully defrosted/defogged, but I thought it worth mentioning since I know other people have had same issue/complaint and knowing that the car would greatly benefit from some additional rear air ducts (for both heating and cooling).
Rear defroster: works fine most of the time but it's the 5-10 occurrences in 2 winters when I'm driving in falling snow and it can't seem to keep up with melting the snow that falls. Even when starting car up in the morning it just takes longer to melt all the snow/ice than my VW.
I don't mean to compare every feature to VW but I had 2 VW Tiguans before the CX-9 (still have 1 of them in the household) and they just dealt with the cold weather a lot better. That's not to say that the Tiguan did not have its own shortcomings (there's a reason I did not get another Tiguan in 2017), just that I didn't realize I would be encountering so many cold weather issues with the Mazda.
I really do like the CX-9 and want to love it, but I just can't. I'm glad to hear that your CX-9 has not presented all of the same issues but there are certainly enough other people out there with similar experiences to mine. I'm hoping that Mazda can/will address most of these in the future as they seem like easy fixes...but I know that just because something seems easy and/or cheap does not mean it's cost-effective for the manufacturer.