I've been raving mad about this exact shit for years.
I'm not a developer, but I remember how long pre-smartphone would last with little 500mAh batteries. Even after 3g and into 4g connectivity and well after the proliferation of less efficient Bluetooth a phone would last anywhere from 3-14 days between charging.
Now every phone has 3,000-4,000mAh batteries and, besides 5g, the wireless standards have become significantly more efficient.
The only notable offset is the big touch screens, but even those have gotten more efficient, and seems not to matter because standby time is still trash now too.
I doubt there's a continous A/V feed to servers, but 100% our phones are always listening for keywords/phrases locally and then sending "relevant" data back for ads, on top of the always on location tracking.
It's hilarious that phones cost as much as they do, considering how unwieldy and low screen-time they've become, on top of the idea that we're paying to be tracked.
This is correct. I've worked for AT&T, had a co-worker from Verizon, and have been a customer to both.
Manufacturers generally make one model of their device that's fully universal, and then carriers install their own custom tweaked firmware on them.
Verizon is by far the most locked-down and they do not unlock. You would have to flash a custom firmware specifically for the device, and even then there would probably be issues with the bootloader being locked.
It's terrible and infuriating, but you just can't take a Verizon-tainted phone to any other carrier.