I absolutely agree that you can compare the price of an iPhone Pro with an iPad Pro and scratch your head over why they are the same price.
I think the difference is expectations... iPhone Pro does everything that people expect a smartphone would do (and then some). Apple keeps pushing iPad Pro as computer replacement so people's expectation is that it can do what a computer (read: laptop) can do. They have backed off of that marketing lately which really seemed to peak with the "what is a computer" iPad ads. People would actually view iPad Pro as a massive deal if they expected it to have the same functionality as an iPhone with a giant screen.
I don’t have this issue since I never expected tablets to replace my laptop. I’ve also tried some Windows 2-in-1s before and they sucked as tablets.
The iPad just naturally took over laptop duties (mostly web browsing, reading and Netflix/Hulu in bed/couch) as hardware and software improved. Granted, I’m not a fan of the laptop’s clamshell form factor to begin with. When I need to work, I prefer to do it on the desktop with multi-monitor setup plus a more comfortable keyboard and trackball.
Mind, I also remember building $$$ HTPCs since streaming devices were quite limited back then. Now, we have new powerful streaming devices from Roku, Amazon, Google/Android and AppleTV which pretty much all the streaming services support.