Uhm, let's stick to the point about headphone jacks.
Help me understand because you kind of lost me (genuinely), are you saying the premium Pixel models are for people who can afford bluetooth headphones? Therefore that makes it okay to exclude the headphone jack feature? If that's what you mean, how do you account for expensive wired headphones? Being expensive is not exclusive to bluetooth. There are a plethora of cheap and expensive wired and bluetooth accessories. The argument "if you can afford a Pixel 3, you can afford bluetooth accessories" is a weak argument, as is the argument that "if you can only afford the Pixel 3a, you shouldn't spend money on bluetooth. Use your old jacks." As the article points out: "why should that principle only apply to those on a budget?"
I also don't follow what you mean about "some places having far less access" either. Isn't the Pixel 3a being sold in the US market along with the Pixel 3? Don't we all have the same access to bluetooth accessories?
Even if I've understood your post correctly, I'm still not hearing any good reason why Google decided to put the jack in the cheaper model, but not in the more expensive model. It's not about space and it's certainly not about waterproofing (the Pixel 3 itself has the USB C port with full waterproofing). At the very least, it's inconsistent decision making by Google. At worst, it's Google being greedy, which is my leading theory as to why they've done this.
Everything I've heard -- from what you've posted to others saying "I'm living fine without the jack" -- sound like excuses; poor ones at that.
Look, I'm living fine without the jack, too. If I want clean Android software with Google support and the superior camera, I have to live with the Pixel 3. But let's not pretend it's not a mistake for Google to remove the jack -- for no good reason -- from the more expensive models, but include it in the cheaper models. There's no reason to not include the jack in both their affordable phones and their premium phones. In fact, it makes far less sense to me that the premium models don't have it.