You're 100% correct. Google and Apple started this trend, and MS perfected it: just say you're creating "open source" products, but release a closed source version. These mega companies still benefit from the work of clueless software engineers who donate their time to the open source product, but what the mega corps deliver to end users is the closed source version.
Nothing "clueless", I don't know what you are talking about. If people release/contribute to code under MIT license, they are very well aware that anyone on any projects -- open source projects, proprietary software -- can use their code as long as there is a copy of the copyright notice. Otherwise they should release it under GPL or something similar, or spend their time elsewhere. It's all clear and fair game and working as intended for decades.
I wasn't clueless when I built a tiny functionality into Code-OSS and I'm fine with Microsoft (or M$?) slapping telemetry on VSCode. You know, the crash reporter and usage statistics are the foundation of this incredible product/software. People use that software for free and they can disable telemetry at any time.
I'd rather work a week on VSCode for free than spending a day looking at Jetbrains' Java font rendering or waiting for Visual Studio to start.
Apple released OS X/Darwin open source, but kept the moneymaking frameworks (cocoa, carbon) closed source. This generated positive PR while keeping the secret sauce needed to ship polished applications under lock and key
Google released Android open source, but then made unlocking bootloaders and flashing devices as difficult as possible for laymen. So they get to point at AOSP and say "open source" but in practice the vast majority of users end up running proprietary builds with big G's telemetry baked in
Unlocking and flashing Androids is (in general) much easier today than it was 10 years ago, mostly due to Google's efforts with fastboot and other software infrastructure. Modern Pixels are really easy to hack on.
> in practice the vast majority of users end up running proprietary builds with big G's telemetry baked in
The vast majority of users are always going to do this, regardless of how easy it is to install a custom OS.
